Digital BW, The Print

Given all the Genuine Fractals etc discussion I was wondering what people's thoughts were on 
this.  Is it best to lower the dpi and gain size (say 360 down to 300) or interpolate up 
(through whatever method) and maintain the dpi?

Cheers

Steve

I believe it depends on the difference between ones ability to up-rez and
sharpen, vs. what algorithms have been put into the driver, RIP, etc..
Certainly between 300 and 360 we would be talking about pretty subtle
differences that require a demanding eye, and side-by-side review.

Best regards,
John Moody

-----Original Message-----
From: DigitalBlackandWhiteThePrint@yahoogroups.com
[mailto:DigitalBlackandWhiteThePrint@yahoogroups.com]On Behalf Of Steve Kale
Sent: Tuesday, August 23, 2005 9:41 AM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: [Digital BW] Up-rez and print at 360 or print at 300?

Given all the Genuine Fractals etc discussion I was wondering what people's
thoughts were on
this.  Is it best to lower the dpi and gain size (say 360 down to 300) or
interpolate up
(through whatever method) and maintain the dpi?

Cheers

Steve





[Non-text portions of this message have been removed]

I don't know what's "best" - here's what I do: I'm printing to an Epson 
7600 using ImagePrint so I keep my PS print documents (flattened TIFs) 
at 360.  I do all image restoration and processing at the scan 
resolution of 400 dpi.  I use GF to enlarge in 1.5" steps while keeping 
the 400 dpi resolution.  Then use PSCS to convert to 360 dpi so that 
ImagePrint/Epson doesn't do it.  I'm satisfied with B&W that I get off 
the 7600.

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Steve Kale" 
<stevekale@b...> wrote:
> Given all the Genuine Fractals etc discussion I was wondering what 
people's thoughts were on 
> this.  Is it best to lower the dpi and gain size (say 360 down to 
300) or interpolate up 

> (through whatever method) and maintain the dpi?
> 
> Cheers
> 
> Steve

I had always sent prints at 360 because, if I recall correctly, supposedly
the Epson driver for the desktop machines uses 720dpi and hence I was giving
the print driver an easy up-res.  I am not sure what the 4800 driver uses.
I seem to recall the large format drivers using 360.  I guess I will stick
with my 360 and up-scale even if 300 would get me there.

Yea, I would rather send the file over there at 300 or even 240 than
have to resort to upsampling. Through the years I have been amazed at
how efficient the Epson driver is at functioning at less than perfect
file sizes. But, of course this is image and scan dependent. You can
get away with more from a drum scan than a 20D file or a nikon scan
for instance - or from a scan of a bunch of trees than a subtle tonal
gradation. 

John


--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "John Moody"
<moodymz3@y...> wrote:
> I believe it depends on the difference between ones ability to
up-rez and
> sharpen, vs. what algorithms have been put into the driver, RIP, etc..
> Certainly between 300 and 360 we would be talking about pretty subtle
> differences that require a demanding eye, and side-by-side review.
> 
> Best regards,
> John Moody
> 
> -----Original Message-----
> From: DigitalBlackandWhiteThePrint@yahoogroups.com
> [mailto:DigitalBlackandWhiteThePrint@yahoogroups.com]On Behalf Of
Steve Kale
> Sent: Tuesday, August 23, 2005 9:41 AM
> To: DigitalBlackandWhiteThePrint@yahoogroups.com
> Subject: [Digital BW] Up-rez and print at 360 or print at 300?
> 
> Given all the Genuine Fractals etc discussion I was wondering what
people's
> thoughts were on
> this.  Is it best to lower the dpi and gain size (say 360 down to
300) or

> interpolate up
> (through whatever method) and maintain the dpi?
> 
> Cheers
> 
> Steve
> 
> 
> 
> 
> 
> [Non-text portions of this message have been removed]

Steve Kale wrote:

>I had always sent prints at 360 because, if I recall correctly, supposedly
>the Epson driver for the desktop machines uses 720dpi and hence I was giving
>the print driver an easy up-res.  I am not sure what the 4800 driver uses.
>I seem to recall the large format drivers using 360.  I guess I will stick
>with my 360 and up-scale even if 300 would get me there.
>
>  
>
Some fine modes of the 4000-7600-9600 Epson drivers have 720 PPI native 
resolution as well so I expect the same for the 4800.

With Qimage I do not worry what I send to the printer. The file can be 
kept in its original (scan) format and the up or down sampling to the 
driver's native resolution is done well with Qimage. If there's an 
overload of information: 6x6 or 6x9 scanned at 4000 PPI and used for (a 
series of) a small print(s) then I tend to do a downsample to 360 PPI as 
otherwise it takes much more time in processing, Qimage's interpolation 
etc settings on "off" then. That file goes in the dustbin afterwards.

Ernst

Steve,
growing curiosity was pushed over the edge into action by your post. I
did  not have time to do a comprehensive test but was curious to see
the magnitude of any effects.  

My mono printer is a 1270 with some MIS UT FSN inks - not the whole
set and used with my own curves (which are OK but not perfect).  This
is clearly non-standard so I also carried out the same experiment in
colour on a 1290 with MIS archival inks, and also in BO with eboni on
the 1290).  

Normally I feed the printers with 200 ~ 360 ppi images.  I expected
that the 200 dpi end would be the best test.  

Question: is there a significant difference in the appearance of a 200
ppi image sent to the 1270/1290 EPSON drivers compared to the same
image printed after first interpolating by a known algorithm.
  
The most convenient pre-print interpolation I had available was to use
Picture Window Pro. In a pre-test I looked at both bicubic with 16.7%
sharpening and Lanczos 6x6 and, given how close the results were in
that test decided to use the former method for the other tests. (I do
not posses PS.)  Interpolation was done to 720 ppi. Prints were all to
 the same size (about 10"x15").

The test image was of some tree canopies in generally high contrast
lighting, with sharp, unsharp, high-contrast and low-contrast areas. 
There was some image noise in the lower zones, from the camera, I
suspected that such noise might be a good way to distinguish the
methods. A wider range of test images would, naturally, be needed to
form a firm conclusion.

Answer: the interim conclusion is that differences due to the method
of resampling were very minor.  There were just-perceptible
differences in the background "noise" in some dark-mid-tone
out-of-focus areas, but nothing else I could distinguish from 10 inch
viewing distance in good light.  I suspect that very small
changes to sharpening explain the difference (on second thoughts this
is pretty obvious: the processes involved are linear and include
interpolation and sharpening, with what comes down to, probably, tiny
differnces in the "effective" kernel for the whole process if it were
to be reduced to a single step).  Perhaps the "smart" approach in
Qimage is different - I downloaded it to try but had some problems and
do not now have time to test it properly. 

What now? At the moment this aspect is not going to be my highest
priority in terms of workflow improvement, so no more tests in the
immediate future, and I'll trust the drivers to do the (modest)
resampling. 

If someone is surprised by this, I'd love to hear the details of the
contrary evidence, as I could quite easily have missed an important
point in what was a cursory test.  I find it quite probable that the
methods in the printer drivers break down when the resampling ratio
gets too large, but that is not happening in the regime in which I
work.

This post has grown too long.

Ken



--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Steve Kale"
<stevekale@b...> wrote:
> Given all the Genuine Fractals etc discussion I was wondering what
people's thoughts were on 
> this.  Is it best to lower the dpi and gain size (say 360 down to
300) or interpolate up 

> (through whatever method) and maintain the dpi?
> 
> Cheers
> 
> Steve

"kenstrain2000" <kenstrain2000@y...> wrote:
...
> Question: is there a significant difference in the appearance of a 200
> ppi image sent to the 1270/1290 EPSON drivers compared to the same
> image printed after first interpolating by a known algorithm.
...
> Answer: the interim conclusion is that differences due to the method
> of resampling were very minor.  

I had the same result a several years ago and stopped adjusting images
to a magic dpi before printing. Bicubic was the best interpolator that
I had at the time. The Epson diffusion dithering seems to hide most
interpolation artifacts in normal photo images.  The entire issue went
away when I switched to Qimage printing.

You might see more of a difference with one of the fancy interpolation
+ print sharpening applications like QI.

John & Steve,

A belated reply, but after years of discussing this on the old Epson-Inkjet 
list, Kennedy McEwan (who designs digital electronic kit) summed it up by 
advising that:-

    if the ppi is between 240 and 480 at your print size, leave it as it is. 
If it is below 240ppi, upsample to             360ppi, and if it is above 
480ppi, downsample to 360ppi.

All Epson desktops upsample in the driver (by various methods?) to 720ppi, 
old wideformats to 360ppi, and newer wideformats to 360 or 720ppi.

Although ppi that are not integers of 720 give rise to aliasing patterns 
with images of repeating patterns, with normal images this is unlikely to be 
seen. Upsampling to 720ppi as QImage does can also apparently have some 
undesirable side-effects, but they are also not normally seen. Upsampling to 
720ppi in QImage gives you the option of using better upsampling algorithms 
than those that are used in the Epson driver, but of course 720ppi images 
get rather large!

There is no magic at all in the widely-used 300ppi; it will lead to aliasing 
with patterns, and apparently arose simply because it is 2x a 150lpi 
line-screen.

Tests have shown that people can see improvements in resolution up to about 
600ppi (if you have that genuine resolution), and some recent printers can 
resolve lines at about the same resolution.

Bob Frost.

----- Original Message ----- 
From: "john dean" <deanwork2003@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Tuesday, August 23, 2005 3:49 PM
Subject: Re: [Digital BW] Up-rez and print at 360 or print at 300?



Yea, I would rather send the file over there at 300 or even 240 than
have to resort to upsampling. Through the years I have been amazed at
how efficient the Epson driver is at functioning at less than perfect
file sizes. But, of course this is image and scan dependent. You can
get away with more from a drum scan than a 20D file or a nikon scan
for instance - or from a scan of a bunch of trees than a subtle tonal
gradation.

John


--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "John Moody"
<moodymz3@y...> wrote:
> I believe it depends on the difference between ones ability to
up-rez and
> sharpen, vs. what algorithms have been put into the driver, RIP, etc..
> Certainly between 300 and 360 we would be talking about pretty subtle
> differences that require a demanding eye, and side-by-side review.
>
> Best regards,
> John Moody
>
> -----Original Message-----
> From: DigitalBlackandWhiteThePrint@yahoogroups.com
> [mailto:DigitalBlackandWhiteThePrint@yahoogroups.com]On Behalf Of
Steve Kale
> Sent: Tuesday, August 23, 2005 9:41 AM
> To: DigitalBlackandWhiteThePrint@yahoogroups.com
> Subject: [Digital BW] Up-rez and print at 360 or print at 300?
>
> Given all the Genuine Fractals etc discussion I was wondering what
people's
> thoughts were on
> this.  Is it best to lower the dpi and gain size (say 360 down to
300) or
> interpolate up
> (through whatever method) and maintain the dpi?
>
> Cheers
>
> Steve
>
>
>
>
>
> [Non-text portions of this message have been removed]






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