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2003-11-29 by Paul Roark
Photoshop CS just made me very happy. The full sepia curve for my latest dual-toner 1280 inkset had visible stair-steps with RGB 8-bit/channel printing. When I converted the test file to 16 bit/channel just before applying the curves, it printed with no artifacts through the Epson driver. Paul www.PaulRoark.com <http://www.paulroark.com/> [Non-text portions of this message have been removed]
2003-11-29 by Tom Baker
Paul - What would be the result if you had started with a 16bit image, done all of your work, including the curves application, then converted to 8bit just before printing? Similarly, what happens if you apply the curve before converting to 16 bit in your most recent scenario? The reason I ask is that I'm still wondering if, when, and how it makes a difference if you print an 8 or 16bit gray file. I've printed some 8bit files that look just fine. But, that seems illogical. Tom Baker Paul Roark <paul.roark@...> wrote: Photoshop CS just made me very happy. The full sepia curve for my latest dual-toner 1280 inkset had visible stair-steps with RGB 8-bit/channel printing. When I converted the test file to 16 bit/channel just before applying the curves, it printed with no artifacts through the Epson driver. Paul www.PaulRoark.com <http://www.paulroark.com/> [Non-text portions of this message have been removed] Yahoo! Groups Sponsor Please visit the Group Homepage to check the Files, Bookmarks, Polls and other resources as they are often being updated. The page is at: http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint If you wish to receive no emails or just a daily digest, or you wish to unsubscribe, please edit your Membership preferences by visiting this same page. Please follow these basic guidelines: - Include your full name with your message. - Include the address of your website, if you have one. - As threads develop, trim off excess portions of earlier messages to keep them short. - As the topic of a thread changes remember to change the subject header. - Good manners are required at all time. No personal attacks or flames - Complete your Yahoo profile. - Before posting a question, search the message archives and the various resources on the homepage. Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. [Non-text portions of this message have been removed]
2003-11-29 by Martin Wesley
* -----Original Message----- * From: Paul Roark [mailto:paul.roark@...] * Sent: Friday, November 28, 2003 9:37 PM * To: DigitalB&WPrint * Subject: [Digital BW] 16 bit printing * * * Photoshop CS just made me very happy. * * * * The full sepia curve for my latest dual-toner 1280 inkset had * visible stair-steps with RGB 8-bit/channel printing. When I * converted the test file to 16 bit/channel just before * applying the curves, it printed with no artifacts through the * Epson driver. * Paul, Nice, huh? <G> I think this may overcome one of the inherent problems with RGB separation curve workflows. In 8-bit the curves really stressed the image data and if the data was already on the edge you could wind up with problems in the final print. Staying in 16-bit you have a much, much larger margin for error. Martin Wesley http://www.carolyn.cc/Guests/MartinWesley/pages/MW_01.html http://www.borderless-photos.de/guests.html
2003-11-29 by Martin Wesley
* -----Original Message----- * From: Tom Baker [mailto:tbaker1328@sbcglobal.net] * Sent: Friday, November 28, 2003 9:46 PM * To: DigitalBlackandWhiteThePrint@yahoogroups.com * Subject: Re: [Digital BW] 16 bit printing * * * Paul - * * What would be the result if you had started with a 16bit * image, done all of your work, including the curves * application, then converted to 8bit just before printing? * Similarly, what happens if you apply the curve before * converting to 16 bit in your most recent scenario? The * reason I ask is that I'm still wondering if, when, and how it * makes a difference if you print an 8 or 16bit gray file. * I've printed some 8bit files that look just fine. But, that * seems illogical. * Tom, I'll put my 2 cents in here if you don't mind. For the most part you can make great prints working and printing in 8-bit mode. If you couldn't then we would not have gotten as far with this as we have. However, it is desirable to do everything in a higher bit mode. As you adjust an image you can start to chop up the data in 8-bit to the extent that not all of the 256 shades of gray are used and your histogram appears "combed" and/or fuzzy. You can actually have quite a lot of this and still get a good print but you frequently wind up with problems of posterization and tonal flat spots in areas like skin or skies. In 16-bit with 65,536 shades of gray you can lose thousands of shades and it will never be visible in the print. Many people have always worked their prints from beginning to end in 16-bit mode but for the majority the lack of layers and other tools in 16-bit mode was not acceptable and we dropped down to 8-bit after making some initial adjustments. The great thing about Photoshop CS is that you now have all of the tools and layers available in 16-bit that you had in 8-bit. The bad news is that the working file sizes get really out of hand as you start adding layers in 16-bit mode. However, the good news is that you can save an initial 16-bit version of your file and then an 8-bit version. Work out all of your layers and adjustments in the 8-bit file. When you are done put all the layers in a layer folder, open up the 16-bit version of the image you saved, drag the layer folder from the 8-bit to the 16-bit image and presto you have a 16-bit file that is identical to what you would have had if you had done all the work in 16-bit. Very cool! In PS7 and earlier if you did all of your adjustments in 16-bit and then converted to 8-bit before applying the RGB separation curves you would "damage" the image data when the curves were applied. Might or might not effect image quality depending upon the image. Same thing if you applied the curves to an 8-bit file prior to converting to 16-bit. Once the damage has been done in 8-bit converting to 16-bit does not help. If you were not using RGB separation curves, then converting from 16-bit to 8-bit prior to printing would not cause you any problems. However, there is no reason to convert a 16-bit file to 8-bit prior to applying the curve or prior to printing. Just print directly from 16-bit. Martin Wesley http://www.carolyn.cc/Guests/MartinWesley/pages/MW_01.html http://www.borderless-photos.de/guests.html
2003-11-29 by Paul Roark
Tom & Martin, Yes, we've got some new 16-bit questions to explore here. I sure don't want to deal with huge 16-bit/channel, multiple-layer files, but for this one step of applying a curve whose shape just was too much for 8-bit/color to handle smoothly, it sure saved the day (or what's left of it). Gustav Le Gray reproduction: c=49, m=61, y=74. The full sepia curve & UT-2: c=49, m=63, y=74. Yes! Paul www.PaulRoark.com _____________________________________
-----Original Message----- From: Martin Wesley [mailto:mwesley250@...] Sent: Friday, November 28, 2003 9:52 PM To: DigitalBlackandWhiteThePrint@yahoogroups.com Subject: RE: [Digital BW] 16 bit printing * -----Original Message----- * From: Paul Roark [mailto:paul.roark@...] * Sent: Friday, November 28, 2003 9:37 PM * To: DigitalB&WPrint * Subject: [Digital BW] 16 bit printing * * * Photoshop CS just made me very happy. * * * * The full sepia curve for my latest dual-toner 1280 inkset had * visible stair-steps with RGB 8-bit/channel printing. When I * converted the test file to 16 bit/channel just before * applying the curves, it printed with no artifacts through the * Epson driver. * Paul, Nice, huh? <G> I think this may overcome one of the inherent problems with RGB separation curve workflows. In 8-bit the curves really stressed the image data and if the data was already on the edge you could wind up with problems in the final print. Staying in 16-bit you have a much, much larger margin for error. Martin Wesley http://www.carolyn.cc/Guests/MartinWesley/pages/MW_01.html http://www.borderless-photos.de/guests.html Please visit the Group Homepage to check the Files, Bookmarks, Polls and other resources as they are often being updated. The page is at: http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint If you wish to receive no emails or just a daily digest, or you wish to unsubscribe, please edit your Membership preferences by visiting this same page. Please follow these basic guidelines: - Include your full name with your message. - Include the address of your website, if you have one. - As threads develop, trim off excess portions of earlier messages to keep them short. - As the topic of a thread changes remember to change the subject header. - Good manners are required at all time. No personal attacks or flames - Complete your Yahoo profile. - Before posting a question, search the message archives and the various resources on the homepage. Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
2003-11-29 by Ernst Dinkla
Where are actually the bottlenecks of a 16 bit workflow ? True 16 bit scanning is possible on some scanners meanwhile, the difference with the ones that do a 14 bit A/D conversion will be hardly noticeable. Bitmap editors like PWP and PS now allow full 16 bit editing. At the end of the workflow the printer engine itself will be only available as 8 bit, if it actually produces 255 steps per colour on the paper we will already be very happy and probably we will never notice it when it produces only 230 steps or less. Are there 16 bit printengines ? Lightjets etc ? That it will only show in transparencies is another matter. What is more of a question is what printer drivers actually do. The printer drivers usually work with a 16 bit conversion table internally to get better rounding off. That is always used whether it is getting 8 bit or 16 bit channel data as its source. Windows reduces all printerdriver output data to 8 bit when it uses the Windows spooling. There are ways to overcome that but when the printerengines don't take higher than 8 either it has no sense. Gimp-print used 16 bit conversion tables but I really do not know how much 16 bit it is throughout now, no 8 bit filter at the input ?, no 8 bit filter at the output? Same questions for OS X. I also wonder whether the Epson drivers normally filter the input to 8 bit and only use 16 bit conversion tables internally to drop to 8 bit as soon as possible again. Speed is a factor in all that. Roy must know the Gimp-print details ............. Ernst
2003-11-29 by Tom Baker
Martin - I know all of that. But, it 'feels' like something is going on in the end-to-end process that seems to fly in the face of the numbers/theories. In the end we may not need 16 bit throughout the process to get max print quality. Or, at least, not have to work in 16 bit all of the time. Maybe there are improvements in the 8bit processing that the image processors do. If it is, in fact, true that the print engines all work in 8 bit, then: 1.) maybe we can drop back to 8 bit sooner in the workflow without degradation, or 2.) what kind of quality increase could we see if the print engines were 16 bit. Just thinking out loud. Tom Baker Martin Wesley <mwesley250@...> wrote: * -----Original Message----- * From: Tom Baker [mailto:tbaker1328@...] * Sent: Friday, November 28, 2003 9:46 PM * To: DigitalBlackandWhiteThePrint@yahoogroups.com * Subject: Re: [Digital BW] 16 bit printing * * * Paul - * * What would be the result if you had started with a 16bit * image, done all of your work, including the curves * application, then converted to 8bit just before printing? * Similarly, what happens if you apply the curve before * converting to 16 bit in your most recent scenario? The * reason I ask is that I'm still wondering if, when, and how it * makes a difference if you print an 8 or 16bit gray file. * I've printed some 8bit files that look just fine. But, that * seems illogical. * Tom, I'll put my 2 cents in here if you don't mind. For the most part you can make great prints working and printing in 8-bit mode. If you couldn't then we would not have gotten as far with this as we have. However, it is desirable to do everything in a higher bit mode. As you adjust an image you can start to chop up the data in 8-bit to the extent that not all of the 256 shades of gray are used and your histogram appears "combed" and/or fuzzy. You can actually have quite a lot of this and still get a good print but you frequently wind up with problems of posterization and tonal flat spots in areas like skin or skies. In 16-bit with 65,536 shades of gray you can lose thousands of shades and it will never be visible in the print. Many people have always worked their prints from beginning to end in 16-bit mode but for the majority the lack of layers and other tools in 16-bit mode was not acceptable and we dropped down to 8-bit after making some initial adjustments. The great thing about Photoshop CS is that you now have all of the tools and layers available in 16-bit that you had in 8-bit. The bad news is that the working file sizes get really out of hand as you start adding layers in 16-bit mode. However, the good news is that you can save an initial 16-bit version of your file and then an 8-bit version. Work out all of your layers and adjustments in the 8-bit file. When you are done put all the layers in a layer folder, open up the 16-bit version of the image you saved, drag the layer folder from the 8-bit to the 16-bit image and presto you have a 16-bit file that is identical to what you would have had if you had done all the work in 16-bit. Very cool! In PS7 and earlier if you did all of your adjustments in 16-bit and then converted to 8-bit before applying the RGB separation curves you would "damage" the image data when the curves were applied. Might or might not effect image quality depending upon the image. Same thing if you applied the curves to an 8-bit file prior to converting to 16-bit. Once the damage has been done in 8-bit converting to 16-bit does not help. If you were not using RGB separation curves, then converting from 16-bit to 8-bit prior to printing would not cause you any problems. However, there is no reason to convert a 16-bit file to 8-bit prior to applying the curve or prior to printing. Just print directly from 16-bit. Martin Wesley http://www.carolyn.cc/Guests/MartinWesley/pages/MW_01.html http://www.borderless-photos.de/guests.html Yahoo! Groups Sponsor Please visit the Group Homepage to check the Files, Bookmarks, Polls and other resources as they are often being updated. The page is at: http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint If you wish to receive no emails or just a daily digest, or you wish to unsubscribe, please edit your Membership preferences by visiting this same page. Please follow these basic guidelines: - Include your full name with your message. - Include the address of your website, if you have one. - As threads develop, trim off excess portions of earlier messages to keep them short. - As the topic of a thread changes remember to change the subject header. - Good manners are required at all time. No personal attacks or flames - Complete your Yahoo profile. - Before posting a question, search the message archives and the various resources on the homepage. Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. [Non-text portions of this message have been removed]
2003-11-29 by A. Huntley
Martin, > The great thing about Photoshop CS is that you now have all of the tools and > layers available in 16-bit that you had in 8-bit. The bad news is that the > working file sizes get really out of hand as you start adding layers in > 16-bit mode. However, the good news is that you can save an initial 16-bit > version of your file and then an 8-bit version. Work out all of your layers > and adjustments in the 8-bit file. When you are done put all the layers in a > layer folder, open up the 16-bit version of the image you saved, drag the > layer folder from the 8-bit to the 16-bit image and presto you have a 16-bit > file that is identical to what you would have had if you had done all the > work in 16-bit. Very cool! This is about the most useful tip I've seen on this forum for quite some time now. I'm definitely going to try this technique with my somewhat immense LF files; several have gone over 1GB working up the image in 16-bit mode all the way through! Thank you, Alan Huntley
2003-11-29 by Roy Harrington
--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Ernst Dinkla" <E.Dinkla@c...> wrote: > Where are actually the bottlenecks of a 16 bit workflow ? > > True 16 bit scanning is possible on some scanners meanwhile, the > difference with the ones that do a 14 bit A/D conversion will be > hardly noticeable. > Bitmap editors like PWP and PS now allow full 16 bit editing. > At the end of the workflow the printer engine itself will be only > available as 8 bit, if it actually produces 255 steps per colour > on the paper we will already be very happy and probably we will > never notice it when it produces only 230 steps or less. Are > there 16 bit printengines ? Lightjets etc ? That it will only > show in transparencies is another matter. > > What is more of a question is what printer drivers actually do. > The printer drivers usually work with a 16 bit conversion table > internally to get better rounding off. That is always used > whether it is getting 8 bit or 16 bit channel data as its source. > Windows reduces all printerdriver output data to 8 bit when it > uses the Windows spooling. There are ways to overcome that but > when the printerengines don't take higher than 8 either it has no > sense. Gimp-print used 16 bit conversion tables but I really do > not know how much 16 bit it is throughout now, no 8 bit filter at > the input ?, no 8 bit filter at the output? Same questions for > OS X. I also wonder whether the Epson drivers normally filter the > input to 8 bit and only use 16 bit conversion tables internally > to drop to 8 bit as soon as possible again. Speed is a factor in > all that. > > Roy must know the Gimp-print details ............. > > Ernst It was interesting to read that Paul has seen real print evidence of 8 bit versus 16 bit in the curves. Gimp-print and I'd bet all the Epson drivers use 16 bit internally. In the realm where the numbers represent "human" perceived values, 8 bit or 256 values is plenty for all practical purposes. But once you get into the driver the values eventually have to represent quantities of ink on the paper. So while the ratio between 10%K and 100%K in our PS files is a factor of 10x, when you get to ink on the page this could easily be a factor of 1000x in ink volume, which is why 16 bits are needed. All the QuadToneRIP and Gimp-print code starts with 8 bit from the image data files, converts to 16 bit first and then all curves, dithering, etc. stays with 16 bit. (BTW, this is analogous to the need for 16 bit in scanning where the raw values represent light energy values). What Paul does with RGB separation curves is very much like part of the driver conversion to ink volumes. So it not too surprising that he can get some improvement using 16bit. I don't know if the Windows print spooler chops down to 8bit and if it does whether it does it "intellegently" like PS does. (Maybe PS chops before sending?). I haven't found a way so far to get 16 bits throught the OS X printing system either. Roy
2003-11-29 by Paul Roark
I think it is just in the application of the curves where I'm seeing the difference in smoothness. For example, I took the usual 8-bit g/s test file, converted it to 16 bit RGB, applied the sepia printing curve, then converted back to 8-bit/channel RGB, and printed it through the Epson 1280 driver. The final print was identical to the one that was left in 16 bit for printing. So, I suspect the issue is whether it's faster to have Photoshop convert back to 8-bit or leave it there and let the driver do its thing -- whatever that may be. (I have not timed the processes.) Paul www.PaulRoark.com ___________________________________ * -----Original Message----- * From: Paul Roark [mailto:paul.roark@...] * Sent: Friday, November 28, 2003 9:37 PM * To: DigitalB&WPrint * Subject: [Digital BW] 16 bit printing * * * Photoshop CS just made me very happy. * * * * The full sepia curve for my latest dual-toner 1280 inkset had * visible stair-steps with RGB 8-bit/channel printing. When I * converted the test file to 16 bit/channel just before * applying the curves, it printed with no artifacts through the * Epson driver. *
2003-11-29 by Bob Frost
Roy, According to RW PS, photoshop converts to 8bit just before sending to an Epson printer, after any profile conversion in PS. Bob Frost. ----- Original Message -----
From: "Roy Harrington" <roy@...> > don't know if the Windows print spooler chops down to 8bit > and if it does whether it does it "intellegently" like PS does. > (Maybe PS chops before sending?). I haven't found a way so > far to get 16 bits throught the OS X printing system either.
2003-11-29 by Ernst Dinkla
----- Original Message -----
From: "Roy Harrington" <roy@...> To: <DigitalBlackandWhiteThePrint@yahoogroups.com> Sent: Saturday, November 29, 2003 7:47 PM Subject: Re: [Digital BW] 16 bit printing > --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Ernst Dinkla" > <E.Dinkla@c...> wrote: > > Where are actually the bottlenecks of a 16 bit workflow ? > > > > True 16 bit scanning is possible on some scanners meanwhile, the > > difference with the ones that do a 14 bit A/D conversion will be > > hardly noticeable. > > Bitmap editors like PWP and PS now allow full 16 bit editing. > > At the end of the workflow the printer engine itself will be only > > available as 8 bit, if it actually produces 255 steps per colour > > on the paper we will already be very happy and probably we will > > never notice it when it produces only 230 steps or less. Are > > there 16 bit printengines ? Lightjets etc ? That it will only > > show in transparencies is another matter. > > > > What is more of a question is what printer drivers actually do. > > The printer drivers usually work with a 16 bit conversion table > > internally to get better rounding off. That is always used > > whether it is getting 8 bit or 16 bit channel data as its source. > > Windows reduces all printerdriver output data to 8 bit when it > > uses the Windows spooling. There are ways to overcome that but > > when the printerengines don't take higher than 8 either it has no > > sense. Gimp-print used 16 bit conversion tables but I really do > > not know how much 16 bit it is throughout now, no 8 bit filter at > > the input ?, no 8 bit filter at the output? Same questions for > > OS X. I also wonder whether the Epson drivers normally filter the > > input to 8 bit and only use 16 bit conversion tables internally > > to drop to 8 bit as soon as possible again. Speed is a factor in > > all that. > > > > Roy must know the Gimp-print details ............. > > > > Ernst > > > It was interesting to read that Paul has seen real print evidence > of 8 bit versus 16 bit in the curves. Gimp-print and I'd bet all > the Epson drivers use 16 bit internally. In the realm where the > numbers represent "human" perceived values, 8 bit or 256 values > is plenty for all practical purposes. But once you get into the > driver the values eventually have to represent quantities of ink > on the paper. So while the ratio between 10%K and 100%K > in our PS files is a factor of 10x, when you get to ink on the page > this could easily be a factor of 1000x in ink volume, which is > why 16 bits are needed. All the QuadToneRIP and Gimp-print > code starts with 8 bit from the image data files, converts to > 16 bit first and then all curves, dithering, etc. stays with 16 bit. > (BTW, this is analogous to the need for 16 bit in scanning where > the raw values represent light energy values). > > What Paul does with RGB separation curves is very much like > part of the driver conversion to ink volumes. So it not too > surprising that he can get some improvement using 16bit. I > don't know if the Windows print spooler chops down to 8bit > and if it does whether it does it "intellegently" like PS does. > (Maybe PS chops before sending?). I haven't found a way so > far to get 16 bits throught the OS X printing system either. > > Roy Some months ago I asked Mike Chaney (Qimage fame) some information on that subject and got the following answers: > On the colorsync list the question is asked whether the Epson > driver itself accepts 8 or 16 bit files. Internally it will work > in 16 bit (or higher) calculations somewhere like the Gimp-print > driver does. I wonder whether the output to the driver of > PhotoShop itself isn't limited to 8 bit, printing with PS > Elements with the same settings delivers the same quality while > it is only 8 bits. Does Qimage deliver 16 bit to the driver and > have you any idea whether the Epson driver keeps it at that level > throughout the calculations till it drops to the 8 bit level data > for the printer ? It is impossible to pass 48 bit image data (16 bits/channel) to *any* Windows print driver. The Windows API commands that all printing software uses to send data to the driver are all based in 24 bit (8 bit/channel). Since Windows itself does not provide a means to pass anything but 24 bit images to the driver, all software must use the 24 bit methods. If the Epson driver does anything in 48 bit mode, it is doing it after it receives the initial image in 24 bits. Mike > That tells a lot. So if there are drivers that have 48 bit input > they have to bypass the API side of things. I have the Wasatch > SoftRip too and it tries to stay away from much Windows > interference but I haven't found a way of 48 bit input in that > RIP either so there the bottleneck is at the frontside at least. > Whether it actually is a bottleneck is another matter. > > Wonder what Macs do in the process. > > Any objection that I quote your reply in the colorsync list ? No objection at all. As far as I know, all Windows print drivers are designed to accept data "the Windows way" via 24 bit "bitmaps" so even if you had a third party RIP that could somehow do 48 bit, it is unlikely that you'd be able to send data to it at 48 bit anyway unless you had a special plugin that knew how that particular driver supported 48 bit. The bottom line is that you'll never get 48 bit data to a printer using the Windows standard "File", "Print" command in any software because "File", "Print" uses the Windows standard of 24 bit. I'm only telling you this because manufacturers could probably figure out a way to send 48 bit data through the normal Windows API print driver calls (such as sending two 24 bit images that overlay) but to do that, you'd have to have software that also used the same [clever] method of getting 48 bits to the driver which still amounts to specialized printing software to get the job done. Mike (end of quotes) Ernst
2003-11-29 by Ernst Dinkla
----- Original Message -----
From: "Roy Harrington" <roy@...> To: <DigitalBlackandWhiteThePrint@yahoogroups.com> Sent: Saturday, November 29, 2003 7:47 PM Subject: Re: [Digital BW] 16 bit printing > It was interesting to read that Paul has seen real print evidence > of 8 bit versus 16 bit in the curves. Gimp-print and I'd bet all > the Epson drivers use 16 bit internally. In the realm where the > numbers represent "human" perceived values, 8 bit or 256 values > is plenty for all practical purposes. But once you get into the > driver the values eventually have to represent quantities of ink > on the paper. So while the ratio between 10%K and 100%K > in our PS files is a factor of 10x, when you get to ink on the page > this could easily be a factor of 1000x in ink volume, which is > why 16 bits are needed. All the QuadToneRIP and Gimp-print > code starts with 8 bit from the image data files, converts to > 16 bit first and then all curves, dithering, etc. stays with 16 bit. > (BTW, this is analogous to the need for 16 bit in scanning where > the raw values represent light energy values). > > What Paul does with RGB separation curves is very much like > part of the driver conversion to ink volumes. So it not too > surprising that he can get some improvement using 16bit. I > don't know if the Windows print spooler chops down to 8bit > and if it does whether it does it "intellegently" like PS does. > (Maybe PS chops before sending?). I haven't found a way so > far to get 16 bits throught the OS X printing system either. > > Roy Roy, Paul could see a better rounding off in the curves computations. And that quality could survive the Windows drop to 8 bit at the driver input + the 16 bit juggling in the driver + its 8 bit output to the printer. There's still one improvement possible: 16 bit input to the driver in Windows. I could be wrong about 8 bit printer input (driver output) but I think it is unlikely that the printengine is 16 bit per channel. Ernst
2003-11-29 by Martin Wesley
* -----Original Message----- * From: Ernst Dinkla [mailto:E.Dinkla@chello.nl] * Sent: Saturday, November 29, 2003 3:17 AM * To: DigitalBlackandWhiteThePrint@yahoogroups.com * Subject: Re: [Digital BW] 16 bit printing * * * Where are actually the bottlenecks of a 16 bit workflow ? Ernst, Prior to Photoshop CS working in 16-bit was very unattractive compared to 8-bit with layers. In CS file sizes really pull down system performance as layers are added. A file of mind that is a 125MB, 8-bit grayscale with 7 layers has a working file size of 487MB (this is the file size reported by PS when the file is open). The identical file and layers in 16-bit is 250MB, as you would expect, but the working file size climbs to 6.6GB! This is not manageable even on the fastest systems unless you have far more patience than I do. * * True 16 bit scanning is possible on some scanners meanwhile, * the difference with the ones that do a 14 bit A/D conversion * will be hardly noticeable. Bitmap editors like PWP and PS now * allow full 16 bit editing. At the end of the workflow the * printer engine itself will be only available as 8 bit, if it * actually produces 255 steps per colour on the paper we will * already be very happy and probably we will never notice it * when it produces only 230 steps or less. Are there 16 bit * printengines ? Lightjets etc ? That it will only show in * transparencies is another matter. I don't think that there is any advantage to sending 16-bit data to the printer. The only point to working in 16-bit is to ensure that the 8-bit mode data that arrives at the printer has a full 256 steps. As you correctly note, we can get away with far less than 256 but at some point, with some images, you do drop far enough below 256 steps that print quality is degraded. This may be as low as 100 steps or below. I think the threshold may vary from person to person so there would seem to be an advantage to having a large margin for error. 16-bit is overkill. I suspect that for our B&W printing purposes bit modes of 10 (1024) or 12 (4096) would be more than adequate but 16 will definitely do the job. Martin Wesley http://www.carolyn.cc/Guests/MartinWesley/pages/MW_01.html http://www.borderless-photos.de/guests.html * * What is more of a question is what printer drivers actually * do. The printer drivers usually work with a 16 bit conversion * table internally to get better rounding off. That is always * used whether it is getting 8 bit or 16 bit channel data as * its source. Windows reduces all printerdriver output data to * 8 bit when it uses the Windows spooling. There are ways to * overcome that but when the printerengines don't take higher * than 8 either it has no sense. Gimp-print used 16 bit * conversion tables but I really do not know how much 16 bit it * is throughout now, no 8 bit filter at the input ?, no 8 bit * filter at the output? Same questions for OS X. I also wonder * whether the Epson drivers normally filter the input to 8 bit * and only use 16 bit conversion tables internally to drop to 8 * bit as soon as possible again. Speed is a factor in all that. * * Roy must know the Gimp-print details ............. * * Ernst * * * * ------------------------ Yahoo! Groups Sponsor * ---------------------~--> Buy Ink Cartridges or Refill Kits * for your HP, Epson, Canon or Lexmark Printer at MyInks.com. * Free s/h on orders $50 or more to the US & Canada. http://www.c1tracking.com/l.asp?cid=5511 http://us.click.yahoo.com/mOAaAA/3exGAA/qnsNAA/ucIolB/TM ---------------------------------------------------------------------~-> Please visit the Group Homepage to check the Files, Bookmarks, Polls and other resources as they are often being updated. The page is at: http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint If you wish to receive no emails or just a daily digest, or you wish to unsubscribe, please edit your Membership preferences by visiting this same page. Please follow these basic guidelines: - Include your full name with your message. - Include the address of your website, if you have one. - As threads develop, trim off excess portions of earlier messages to keep them short. - As the topic of a thread changes remember to change the subject header. - Good manners are required at all time. No personal attacks or flames - Complete your Yahoo profile. - Before posting a question, search the message archives and the various resources on the homepage. Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
2003-11-29 by Martin Wesley
* -----Original Message----- * From: Tom Baker [mailto:tbaker1328@sbcglobal.net] * Sent: Saturday, November 29, 2003 9:28 AM * To: DigitalBlackandWhiteThePrint@yahoogroups.com * Subject: RE: [Digital BW] 16 bit printing * * * Martin - * * I know all of that. But, it 'feels' like something is going * on in the end-to-end process that seems to fly in the face of * the numbers/theories. In the end we may not need 16 bit * throughout the process to get max print quality. Or, at * least, not have to work in 16 bit all of the time. Maybe * there are improvements in the 8bit processing that the image * processors do. Tom, I agree. I think 8-bit is probably plenty as long as you can preserve the image data during adjustments. I don't think the problem can be addressed with better 8-bit software though. The problem is the limitation of the math. If you change the gamma of an image from 1 to say 2 the only way you can do this if all 256 shades are in use is to reassign pixels to values already in use and leave adjacent values empty with no pixels assigned to them. The number of shades of gray then is reduced from 256. I don't see any way around this. * * If it is, in fact, true that the print engines all work in 8 * bit, then: 1.) maybe we can drop back to 8 bit sooner in the * workflow without degradation, or 2.) what kind of quality * increase could we see if the print engines were 16 bit. In answer to 1.) use Photoshop CS, do all your work in 8-bit on layers and at the end apply the layers to the original 16-bit file. The end result will be a image that has negligible degradation whether you choose to save the end product in 8 or 16-bit mode. You can even save the layer set without the image for future revision of your adjustments. As far as 2.) goes I don't think you would see much if any improvement with a 16-bit printer. I suspect that our ability to differentiate shades of gray may be lower than what you can achieve in 8-bit. If you wanted to increase the bit depth of a print engine I think you would only need to go up to 10 or 12-bit. The highest value I have ever seen published for human perception of shades of gray was in the 900 to 1025 step range and I am skeptical of that. So beyond 10-bit differences would definitely not be discernable to the human eye. Martin * * * * Martin Wesley <mwesley250@...> wrote: * * * * -----Original Message----- * * From: Tom Baker [mailto:tbaker1328@sbcglobal.net] * * Sent: Friday, November 28, 2003 9:46 PM * * To: DigitalBlackandWhiteThePrint@yahoogroups.com * * Subject: Re: [Digital BW] 16 bit printing * * * * * * Paul - * * * * What would be the result if you had started with a 16bit * * image, done all of your work, including the curves * * application, then converted to 8bit just before printing? * * Similarly, what happens if you apply the curve before * * converting to 16 bit in your most recent scenario? The * * reason I ask is that I'm still wondering if, when, and how it * * makes a difference if you print an 8 or 16bit gray file. * * I've printed some 8bit files that look just fine. But, that * * seems illogical. * * * Tom, * * I'll put my 2 cents in here if you don't mind. For the most * part you can make great prints working and printing in 8-bit * mode. If you couldn't then we would not have gotten as far * with this as we have. * * However, it is desirable to do everything in a higher bit * mode. As you adjust an image you can start to chop up the * data in 8-bit to the extent that not all of the 256 shades of * gray are used and your histogram appears "combed" and/or * fuzzy. You can actually have quite a lot of this and still * get a good print but you frequently wind up with problems of * posterization and tonal flat spots in areas like skin or * skies. In 16-bit with 65,536 shades of gray you can lose * thousands of shades and it will never be visible in the print. * * Many people have always worked their prints from beginning to * end in 16-bit mode but for the majority the lack of layers * and other tools in 16-bit mode was not acceptable and we * dropped down to 8-bit after making some initial adjustments. * * The great thing about Photoshop CS is that you now have all * of the tools and layers available in 16-bit that you had in * 8-bit. The bad news is that the working file sizes get really * out of hand as you start adding layers in 16-bit mode. * However, the good news is that you can save an initial 16-bit * version of your file and then an 8-bit version. Work out all * of your layers and adjustments in the 8-bit file. When you * are done put all the layers in a layer folder, open up the * 16-bit version of the image you saved, drag the layer folder * from the 8-bit to the 16-bit image and presto you have a * 16-bit file that is identical to what you would have had if * you had done all the work in 16-bit. Very cool! * * In PS7 and earlier if you did all of your adjustments in * 16-bit and then converted to 8-bit before applying the RGB * separation curves you would "damage" the image data when the * curves were applied. Might or might not effect image quality * depending upon the image. Same thing if you applied the * curves to an 8-bit file prior to converting to 16-bit. Once * the damage has been done in 8-bit converting to 16-bit does not help. * * If you were not using RGB separation curves, then converting * from 16-bit to 8-bit prior to printing would not cause you * any problems. However, there is no reason to convert a 16-bit * file to 8-bit prior to applying the curve or prior to * printing. Just print directly from 16-bit. * * Martin Wesley * http://www.carolyn.cc/Guests/MartinWesley/pages/MW_01.html * http://www.borderless-photos.de/guests.html * * * * Yahoo! Groups Sponsor * Please visit the Group Homepage to check the Files, * Bookmarks, Polls and other resources as they are often being * updated. The page is at: * * http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint * * If you wish to receive no emails or just a daily digest, or * you wish to unsubscribe, please edit your Membership * preferences by visiting this same page. * * Please follow these basic guidelines: * - Include your full name with your message. * - Include the address of your website, if you have one. * - As threads develop, trim off excess portions of earlier * messages to keep them short. * - As the topic of a thread changes remember to change the * subject header. * - Good manners are required at all time. No personal attacks or flames * - Complete your Yahoo profile. * - Before posting a question, search the message archives and * the various resources on the homepage. * * * * * Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. * * * [Non-text portions of this message have been removed] * * * ------------------------ Yahoo! Groups Sponsor * ---------------------~--> Buy Ink Cartridges or Refill Kits * for your HP, Epson, Canon or Lexmark Printer at MyInks.com. * Free s/h on orders $50 or more to the US & Canada. http://www.c1tracking.com/l.asp?cid=5511 http://us.click.yahoo.com/mOAaAA/3exGAA/qnsNAA/ucIolB/TM ---------------------------------------------------------------------~-> Please visit the Group Homepage to check the Files, Bookmarks, Polls and other resources as they are often being updated. The page is at: http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint If you wish to receive no emails or just a daily digest, or you wish to unsubscribe, please edit your Membership preferences by visiting this same page. Please follow these basic guidelines: - Include your full name with your message. - Include the address of your website, if you have one. - As threads develop, trim off excess portions of earlier messages to keep them short. - As the topic of a thread changes remember to change the subject header. - Good manners are required at all time. No personal attacks or flames - Complete your Yahoo profile. - Before posting a question, search the message archives and the various resources on the homepage. Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
2003-11-29 by Tom Baker
Yes, but everything over 8 bits puts you into working in 16 bit mode. A 14 bit scanner is still putting out 16bits. Tom Baker Martin Wesley <mwesley250@...> wrote: * -----Original Message----- * From: Ernst Dinkla [mailto:E.Dinkla@...] * Sent: Saturday, November 29, 2003 3:17 AM * To: DigitalBlackandWhiteThePrint@yahoogroups.com * Subject: Re: [Digital BW] 16 bit printing * * * Where are actually the bottlenecks of a 16 bit workflow ? Ernst, Prior to Photoshop CS working in 16-bit was very unattractive compared to 8-bit with layers. In CS file sizes really pull down system performance as layers are added. A file of mind that is a 125MB, 8-bit grayscale with 7 layers has a working file size of 487MB (this is the file size reported by PS when the file is open). The identical file and layers in 16-bit is 250MB, as you would expect, but the working file size climbs to 6.6GB! This is not manageable even on the fastest systems unless you have far more patience than I do. * * True 16 bit scanning is possible on some scanners meanwhile, * the difference with the ones that do a 14 bit A/D conversion * will be hardly noticeable. Bitmap editors like PWP and PS now * allow full 16 bit editing. At the end of the workflow the * printer engine itself will be only available as 8 bit, if it * actually produces 255 steps per colour on the paper we will * already be very happy and probably we will never notice it * when it produces only 230 steps or less. Are there 16 bit * printengines ? Lightjets etc ? That it will only show in * transparencies is another matter. I don't think that there is any advantage to sending 16-bit data to the printer. The only point to working in 16-bit is to ensure that the 8-bit mode data that arrives at the printer has a full 256 steps. As you correctly note, we can get away with far less than 256 but at some point, with some images, you do drop far enough below 256 steps that print quality is degraded. This may be as low as 100 steps or below. I think the threshold may vary from person to person so there would seem to be an advantage to having a large margin for error. 16-bit is overkill. I suspect that for our B&W printing purposes bit modes of 10 (1024) or 12 (4096) would be more than adequate but 16 will definitely do the job. Martin Wesley http://www.carolyn.cc/Guests/MartinWesley/pages/MW_01.html http://www.borderless-photos.de/guests.html * * What is more of a question is what printer drivers actually * do. The printer drivers usually work with a 16 bit conversion * table internally to get better rounding off. That is always * used whether it is getting 8 bit or 16 bit channel data as * its source. Windows reduces all printerdriver output data to * 8 bit when it uses the Windows spooling. There are ways to * overcome that but when the printerengines don't take higher * than 8 either it has no sense. Gimp-print used 16 bit * conversion tables but I really do not know how much 16 bit it * is throughout now, no 8 bit filter at the input ?, no 8 bit * filter at the output? Same questions for OS X. I also wonder * whether the Epson drivers normally filter the input to 8 bit * and only use 16 bit conversion tables internally to drop to 8 * bit as soon as possible again. Speed is a factor in all that. * * Roy must know the Gimp-print details ............. * * Ernst * * * * ------------------------ Yahoo! Groups Sponsor * ---------------------~--> Buy Ink Cartridges or Refill Kits * for your HP, Epson, Canon or Lexmark Printer at MyInks.com. * Free s/h on orders $50 or more to the US & Canada. http://www.c1tracking.com/l.asp?cid=5511 http://us.click.yahoo.com/mOAaAA/3exGAA/qnsNAA/ucIolB/TM ---------------------------------------------------------------------~-> Please visit the Group Homepage to check the Files, Bookmarks, Polls and other resources as they are often being updated. The page is at: http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint If you wish to receive no emails or just a daily digest, or you wish to unsubscribe, please edit your Membership preferences by visiting this same page. Please follow these basic guidelines: - Include your full name with your message. - Include the address of your website, if you have one. - As threads develop, trim off excess portions of earlier messages to keep them short. - As the topic of a thread changes remember to change the subject header. - Good manners are required at all time. No personal attacks or flames - Complete your Yahoo profile. - Before posting a question, search the message archives and the various resources on the homepage. Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ Yahoo! Groups Sponsor Please visit the Group Homepage to check the Files, Bookmarks, Polls and other resources as they are often being updated. The page is at: http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint If you wish to receive no emails or just a daily digest, or you wish to unsubscribe, please edit your Membership preferences by visiting this same page. Please follow these basic guidelines: - Include your full name with your message. - Include the address of your website, if you have one. - As threads develop, trim off excess portions of earlier messages to keep them short. - As the topic of a thread changes remember to change the subject header. - Good manners are required at all time. No personal attacks or flames - Complete your Yahoo profile. - Before posting a question, search the message archives and the various resources on the homepage. Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. [Non-text portions of this message have been removed]
2003-11-29 by Truman Prevatt
It's called quatization noise. There is extensive literature in the digital signal processing, image processing, SAR processing, Tomographic processing, etc. discussing this issue. In order to maintain a full 8 bits accuracy one must allow additional bits in the processing else the quantization noise will impact the final signal to noise ration. It's in the math - has nothing to do with the image. Once you have your final image an 8 bit image is sufficient since that is probably the limit of the eye. Truman Martin Wesley wrote: > > > * -----Original Message----- > * From: Tom Baker [mailto:tbaker1328@...] > * Sent: Saturday, November 29, 2003 9:28 AM > * To: DigitalBlackandWhiteThePrint@yahoogroups.com > * Subject: RE: [Digital BW] 16 bit printing > * > * > * Martin - > * > * I know all of that. But, it 'feels' like something is going > * on in the end-to-end process that seems to fly in the face of > * the numbers/theories. In the end we may not need 16 bit > * throughout the process to get max print quality. Or, at > * least, not have to work in 16 bit all of the time. Maybe > * there are improvements in the 8bit processing that the image > * processors do. > > Tom, > > I agree. I think 8-bit is probably plenty as long as you can preserve the > image data during adjustments. I don't think the problem can be addressed > with better 8-bit software though. The problem is the limitation of the > math. If you change the gamma of an image from 1 to say 2 the only way you > can do this if all 256 shades are in use is to reassign pixels to values > already in use and leave adjacent values empty with no pixels assigned to > them. The number of shades of gray then is reduced from 256. I don't > see any > way around this. > * > * If it is, in fact, true that the print engines all work in 8 > * bit, then: 1.) maybe we can drop back to 8 bit sooner in the > * workflow without degradation, or 2.) what kind of quality > * increase could we see if the print engines were 16 bit. > > In answer to 1.) use Photoshop CS, do all your work in 8-bit on layers and > at the end apply the layers to the original 16-bit file. The end result > will be a image that has negligible degradation whether you choose to save > the end product in 8 or 16-bit mode. You can even save the layer set > without > the image for future revision of your adjustments. > > As far as 2.) goes I don't think you would see much if any improvement > with > a 16-bit printer. I suspect that our ability to differentiate shades > of gray > may be lower than what you can achieve in 8-bit. If you wanted to increase > the bit depth of a print engine I think you would only need to go up > to 10 > or 12-bit. The highest value I have ever seen published for human > perception > of shades of gray was in the 900 to 1025 step range and I am skeptical of > that. So beyond 10-bit differences would definitely not be discernable to > the human eye. > > Martin > * > * > * > * Martin Wesley <mwesley250@...> wrote: > * > * > * * -----Original Message----- > * * From: Tom Baker [mailto:tbaker1328@...] > * * Sent: Friday, November 28, 2003 9:46 PM > * * To: DigitalBlackandWhiteThePrint@yahoogroups.com > * * Subject: Re: [Digital BW] 16 bit printing > * * > * * > * * Paul - > * * > * * What would be the result if you had started with a 16bit > * * image, done all of your work, including the curves > * * application, then converted to 8bit just before printing? > * * Similarly, what happens if you apply the curve before > * * converting to 16 bit in your most recent scenario? The > * * reason I ask is that I'm still wondering if, when, and how it > * * makes a difference if you print an 8 or 16bit gray file. > * * I've printed some 8bit files that look just fine. But, that > * * seems illogical. > * * > * Tom, > * > * I'll put my 2 cents in here if you don't mind. For the most > * part you can make great prints working and printing in 8-bit > * mode. If you couldn't then we would not have gotten as far > * with this as we have. > * > * However, it is desirable to do everything in a higher bit > * mode. As you adjust an image you can start to chop up the > * data in 8-bit to the extent that not all of the 256 shades of > * gray are used and your histogram appears "combed" and/or > * fuzzy. You can actually have quite a lot of this and still > * get a good print but you frequently wind up with problems of > * posterization and tonal flat spots in areas like skin or > * skies. In 16-bit with 65,536 shades of gray you can lose > * thousands of shades and it will never be visible in the print. > * > * Many people have always worked their prints from beginning to > * end in 16-bit mode but for the majority the lack of layers > * and other tools in 16-bit mode was not acceptable and we > * dropped down to 8-bit after making some initial adjustments. > * > * The great thing about Photoshop CS is that you now have all > * of the tools and layers available in 16-bit that you had in > * 8-bit. The bad news is that the working file sizes get really > * out of hand as you start adding layers in 16-bit mode. > * However, the good news is that you can save an initial 16-bit > * version of your file and then an 8-bit version. Work out all > * of your layers and adjustments in the 8-bit file. When you > * are done put all the layers in a layer folder, open up the > * 16-bit version of the image you saved, drag the layer folder > * from the 8-bit to the 16-bit image and presto you have a > * 16-bit file that is identical to what you would have had if > * you had done all the work in 16-bit. Very cool! > * > * In PS7 and earlier if you did all of your adjustments in > * 16-bit and then converted to 8-bit before applying the RGB > * separation curves you would "damage" the image data when the > * curves were applied. Might or might not effect image quality > * depending upon the image. Same thing if you applied the > * curves to an 8-bit file prior to converting to 16-bit. Once > * the damage has been done in 8-bit converting to 16-bit does not help. > * > * If you were not using RGB separation curves, then converting > * from 16-bit to 8-bit prior to printing would not cause you > * any problems. However, there is no reason to convert a 16-bit > * file to 8-bit prior to applying the curve or prior to > * printing. Just print directly from 16-bit. > * > * Martin Wesley > * http://www.carolyn.cc/Guests/MartinWesley/pages/MW_01.html > * http://www.borderless-photos.de/guests.html > * > * > * > * Yahoo! Groups Sponsor > * Please visit the Group Homepage to check the Files, > * Bookmarks, Polls and other resources as they are often being > * updated. The page is at: > * > * http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint > * > * If you wish to receive no emails or just a daily digest, or > * you wish to unsubscribe, please edit your Membership > * preferences by visiting this same page. > * > * Please follow these basic guidelines: > * - Include your full name with your message. > * - Include the address of your website, if you have one. > * - As threads develop, trim off excess portions of earlier > * messages to keep them short. > * - As the topic of a thread changes remember to change the > * subject header. > * - Good manners are required at all time. No personal attacks or flames > * - Complete your Yahoo profile. > * - Before posting a question, search the message archives and > * the various resources on the homepage. > * > * > * > * > * Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. > * > * > * [Non-text portions of this message have been removed] > * > * > * ------------------------ Yahoo! Groups Sponsor > * ---------------------~--> Buy Ink Cartridges or Refill Kits > * for your HP, Epson, Canon or Lexmark Printer at MyInks.com. > * Free s/h on orders $50 or more to the US & Canada. > http://www.c1tracking.com/l.asp?cid=5511 > http://us.click.yahoo.com/mOAaAA/3exGAA/qnsNAA/ucIolB/TM > ---------------------------------------------------------------------~-> > > Please visit the Group Homepage to check the Files, Bookmarks, Polls and > other resources as they are often being updated. The page is at: > > http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint > > If you wish to receive no emails or just a daily digest, or you wish to > unsubscribe, please edit your Membership preferences by visiting this same > page. > > Please follow these basic guidelines: > - Include your full name with your message. > - Include the address of your website, if you have one. > - As threads develop, trim off excess portions of earlier messages to keep > them short. > - As the topic of a thread changes remember to change the subject header. > - Good manners are required at all time. No personal attacks or flames > - Complete your Yahoo profile. > - Before posting a question, search the message archives and the various > resources on the homepage. > > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > > > > > Yahoo! Groups Sponsor > > > Please visit the Group Homepage to check the Files, Bookmarks, Polls > and other resources as they are often being updated. The page is at: > > http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint > > If you wish to receive no emails or just a daily digest, or you wish > to unsubscribe, please edit your Membership preferences by visiting > this same page. > > Please follow these basic guidelines: > - Include your full name with your message. > - Include the address of your website, if you have one. > - As threads develop, trim off excess portions of earlier messages to > keep them short. > - As the topic of a thread changes remember to change the subject header. > - Good manners are required at all time. No personal attacks or flames > - Complete your Yahoo profile. > - Before posting a question, search the message archives and the > various resources on the homepage. > > > > > Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service > <http://docs.yahoo.com/info/terms/>. [Non-text portions of this message have been removed]
2003-11-30 by Tom Baker
Martin - I don't quiter understand. You get miffed at someone posting color info, or someone saying un-nice things about someone who deservs it, and threaten to cut us off. But, you don't take any action against the culprit. What's up? Tom Baker Martin Wesley <mwesley250@...> wrote: * -----Original Message----- * From: Tom Baker [mailto:tbaker1328@...] * Sent: Saturday, November 29, 2003 9:28 AM * To: DigitalBlackandWhiteThePrint@yahoogroups.com * Subject: RE: [Digital BW] 16 bit printing * * * Martin - * * I know all of that. But, it 'feels' like something is going * on in the end-to-end process that seems to fly in the face of * the numbers/theories. In the end we may not need 16 bit * throughout the process to get max print quality. Or, at * least, not have to work in 16 bit all of the time. Maybe * there are improvements in the 8bit processing that the image * processors do. Tom, I agree. I think 8-bit is probably plenty as long as you can preserve the image data during adjustments. I don't think the problem can be addressed with better 8-bit software though. The problem is the limitation of the math. If you change the gamma of an image from 1 to say 2 the only way you can do this if all 256 shades are in use is to reassign pixels to values already in use and leave adjacent values empty with no pixels assigned to them. The number of shades of gray then is reduced from 256. I don't see any way around this. * * If it is, in fact, true that the print engines all work in 8 * bit, then: 1.) maybe we can drop back to 8 bit sooner in the * workflow without degradation, or 2.) what kind of quality * increase could we see if the print engines were 16 bit. In answer to 1.) use Photoshop CS, do all your work in 8-bit on layers and at the end apply the layers to the original 16-bit file. The end result will be a image that has negligible degradation whether you choose to save the end product in 8 or 16-bit mode. You can even save the layer set without the image for future revision of your adjustments. As far as 2.) goes I don't think you would see much if any improvement with a 16-bit printer. I suspect that our ability to differentiate shades of gray may be lower than what you can achieve in 8-bit. If you wanted to increase the bit depth of a print engine I think you would only need to go up to 10 or 12-bit. The highest value I have ever seen published for human perception of shades of gray was in the 900 to 1025 step range and I am skeptical of that. So beyond 10-bit differences would definitely not be discernable to the human eye. Martin * * * * Martin Wesley <mwesley250@...> wrote: * * * * -----Original Message----- * * From: Tom Baker [mailto:tbaker1328@...] * * Sent: Friday, November 28, 2003 9:46 PM * * To: DigitalBlackandWhiteThePrint@yahoogroups.com * * Subject: Re: [Digital BW] 16 bit printing * * * * * * Paul - * * * * What would be the result if you had started with a 16bit * * image, done all of your work, including the curves * * application, then converted to 8bit just before printing? * * Similarly, what happens if you apply the curve before * * converting to 16 bit in your most recent scenario? The * * reason I ask is that I'm still wondering if, when, and how it * * makes a difference if you print an 8 or 16bit gray file. * * I've printed some 8bit files that look just fine. But, that * * seems illogical. * * * Tom, * * I'll put my 2 cents in here if you don't mind. For the most * part you can make great prints working and printing in 8-bit * mode. If you couldn't then we would not have gotten as far * with this as we have. * * However, it is desirable to do everything in a higher bit * mode. As you adjust an image you can start to chop up the * data in 8-bit to the extent that not all of the 256 shades of * gray are used and your histogram appears "combed" and/or * fuzzy. You can actually have quite a lot of this and still * get a good print but you frequently wind up with problems of * posterization and tonal flat spots in areas like skin or * skies. In 16-bit with 65,536 shades of gray you can lose * thousands of shades and it will never be visible in the print. * * Many people have always worked their prints from beginning to * end in 16-bit mode but for the majority the lack of layers * and other tools in 16-bit mode was not acceptable and we * dropped down to 8-bit after making some initial adjustments. * * The great thing about Photoshop CS is that you now have all * of the tools and layers available in 16-bit that you had in * 8-bit. The bad news is that the working file sizes get really * out of hand as you start adding layers in 16-bit mode. * However, the good news is that you can save an initial 16-bit * version of your file and then an 8-bit version. Work out all * of your layers and adjustments in the 8-bit file. When you * are done put all the layers in a layer folder, open up the * 16-bit version of the image you saved, drag the layer folder * from the 8-bit to the 16-bit image and presto you have a * 16-bit file that is identical to what you would have had if * you had done all the work in 16-bit. Very cool! * * In PS7 and earlier if you did all of your adjustments in * 16-bit and then converted to 8-bit before applying the RGB * separation curves you would "damage" the image data when the * curves were applied. Might or might not effect image quality * depending upon the image. Same thing if you applied the * curves to an 8-bit file prior to converting to 16-bit. Once * the damage has been done in 8-bit converting to 16-bit does not help. * * If you were not using RGB separation curves, then converting * from 16-bit to 8-bit prior to printing would not cause you * any problems. However, there is no reason to convert a 16-bit * file to 8-bit prior to applying the curve or prior to * printing. Just print directly from 16-bit. * * Martin Wesley * http://www.carolyn.cc/Guests/MartinWesley/pages/MW_01.html * http://www.borderless-photos.de/guests.html * * * * Yahoo! Groups Sponsor * Please visit the Group Homepage to check the Files, * Bookmarks, Polls and other resources as they are often being * updated. The page is at: * * http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint * * If you wish to receive no emails or just a daily digest, or * you wish to unsubscribe, please edit your Membership * preferences by visiting this same page. * * Please follow these basic guidelines: * - Include your full name with your message. * - Include the address of your website, if you have one. * - As threads develop, trim off excess portions of earlier * messages to keep them short. * - As the topic of a thread changes remember to change the * subject header. * - Good manners are required at all time. No personal attacks or flames * - Complete your Yahoo profile. * - Before posting a question, search the message archives and * the various resources on the homepage. * * * * * Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. * * * [Non-text portions of this message have been removed] * * * ------------------------ Yahoo! Groups Sponsor * ---------------------~--> Buy Ink Cartridges or Refill Kits * for your HP, Epson, Canon or Lexmark Printer at MyInks.com. * Free s/h on orders $50 or more to the US & Canada. http://www.c1tracking.com/l.asp?cid=5511 http://us.click.yahoo.com/mOAaAA/3exGAA/qnsNAA/ucIolB/TM ---------------------------------------------------------------------~-> Please visit the Group Homepage to check the Files, Bookmarks, Polls and other resources as they are often being updated. The page is at: http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint If you wish to receive no emails or just a daily digest, or you wish to unsubscribe, please edit your Membership preferences by visiting this same page. Please follow these basic guidelines: - Include your full name with your message. - Include the address of your website, if you have one. - As threads develop, trim off excess portions of earlier messages to keep them short. - As the topic of a thread changes remember to change the subject header. - Good manners are required at all time. No personal attacks or flames - Complete your Yahoo profile. - Before posting a question, search the message archives and the various resources on the homepage. Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ Yahoo! Groups Sponsor Please visit the Group Homepage to check the Files, Bookmarks, Polls and other resources as they are often being updated. The page is at: http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint If you wish to receive no emails or just a daily digest, or you wish to unsubscribe, please edit your Membership preferences by visiting this same page. Please follow these basic guidelines: - Include your full name with your message. - Include the address of your website, if you have one. - As threads develop, trim off excess portions of earlier messages to keep them short. - As the topic of a thread changes remember to change the subject header. - Good manners are required at all time. No personal attacks or flames - Complete your Yahoo profile. - Before posting a question, search the message archives and the various resources on the homepage. Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. [Non-text portions of this message have been removed]
2003-11-30 by Martin Wesley
* -----Original Message----- * From: Tom Baker [mailto:tbaker1328@sbcglobal.net] * Sent: Saturday, November 29, 2003 6:54 PM * To: DigitalBlackandWhiteThePrint@yahoogroups.com * Subject: RE: [Digital BW] 16 bit printing * * * Martin - * * I don't quiter understand. You get miffed at someone posting * color info, or someone saying un-nice things about someone * who deservs it, and threaten to cut us off. But, you don't * take any action against the culprit. What's up? * Tom, Benevolent dictatorship. I don't read all the posts. I only check on threads that don't interest me when they seem to run for a long time to see if there is a problem. If the thread has gone off topic or is getting hostile, I simply ask for the thread to be wrapped up and most members are kind enough to comply. If allowed to go on uncheck these types of threads totally destroy the value of the group for the majority of the membership. Some don't get the first message or don't realize I am the group moderator and persist. So I follow it up with a stronger message. If it seems abrupt, my apologies but I really don't feel like spending much time of this sort of thing. If a random check picks up an individual flame I will e-mail the person off list and remind them of group policy. I have no interest or intention of wading through all these posts trying to figure out who is to blame for what. This type of situation tends to make me short tempered and remind me why I quite teaching junior high. Martin Wesley
2003-11-30 by sdmey4@aol.com
In a message dated 11/29/2003 8:07:39 PM Pacific Standard Time, mwesley250@... writes: > This type of situation tends to make me short tempered and remind me why I > quite teaching junior high. > > Martin Wesley > Thank You Martin! I was thinking more like grade school behavior. Having to hit the delete key more than 30 times a day for the same thread makes me short tempered too. Steve Meyers [Non-text portions of this message have been removed]
2003-11-30 by Tom Baker
Martin - That fine. It's really your site, and you can run it as you wish. We're all big kids (if only jr. high level), and know what our options are. I filtered the guy straight to the trash, so I'll just leave it at that. Tom Baker Martin Wesley <mwesley250@...> wrote: * -----Original Message----- * From: Tom Baker [mailto:tbaker1328@...] * Sent: Saturday, November 29, 2003 6:54 PM * To: DigitalBlackandWhiteThePrint@yahoogroups.com * Subject: RE: [Digital BW] 16 bit printing * * * Martin - * * I don't quiter understand. You get miffed at someone posting * color info, or someone saying un-nice things about someone * who deservs it, and threaten to cut us off. But, you don't * take any action against the culprit. What's up? * Tom, Benevolent dictatorship. I don't read all the posts. I only check on threads that don't interest me when they seem to run for a long time to see if there is a problem. If the thread has gone off topic or is getting hostile, I simply ask for the thread to be wrapped up and most members are kind enough to comply. If allowed to go on uncheck these types of threads totally destroy the value of the group for the majority of the membership. Some don't get the first message or don't realize I am the group moderator and persist. So I follow it up with a stronger message. If it seems abrupt, my apologies but I really don't feel like spending much time of this sort of thing. If a random check picks up an individual flame I will e-mail the person off list and remind them of group policy. I have no interest or intention of wading through all these posts trying to figure out who is to blame for what. This type of situation tends to make me short tempered and remind me why I quite teaching junior high. Martin Wesley Yahoo! Groups Sponsor Please visit the Group Homepage to check the Files, Bookmarks, Polls and other resources as they are often being updated. The page is at: http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint If you wish to receive no emails or just a daily digest, or you wish to unsubscribe, please edit your Membership preferences by visiting this same page. Please follow these basic guidelines: - Include your full name with your message. - Include the address of your website, if you have one. - As threads develop, trim off excess portions of earlier messages to keep them short. - As the topic of a thread changes remember to change the subject header. - Good manners are required at all time. No personal attacks or flames - Complete your Yahoo profile. - Before posting a question, search the message archives and the various resources on the homepage. Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. [Non-text portions of this message have been removed]