QTR-Quadtone RIP

Greetings, I’m a new member





I’ve been following this post with interest. But I just got lost.





Eugene can you help me understand why you are concerned about this secret conversion to srgb when “printer manages color is selected” if, as you say you are working in the Windows environment which allows you to select “Photoshop manages color “and initiate an on the fly conversion to the QTR profile, and then select the ABW mode in the Epson driver.





Did I miss something?





Paul Lowry











De : QuadtoneRIP@yahoogroups.com [mailto:QuadtoneRIP@yahoogroups.com]
Envoyé : July-31-16 12:39 PM
À : QuadtoneRIP@yahoogroups.com
Objet : RE: [QuadtoneRIP] Re: QIDF versus ICC





 


Ok I just read the reference you sited (sorry should have done that first),





The article says that if the file has a colour profile it will be CONVERTED to sRGB. If the file does not have a colour profile it will be assumed to be in sRGB (otherwise assigned). It’s not clear in the Dave Polaschek comments when he says “files with attached colour profiles” if he means to exclude greyscale profiles.  I use Adobe 1998 as a workspace so I expect that my files are being converted to sRGB and not assigned.





I can see why colour printers are concerned about this, but I’m not sure we should be. Assigning a profile can change values but converting ( using relative rendering which I’m pretty sure is the default rendering for Photoshop ) cannot,  unless the values are out of gamut and since both spaces go from L*0 to L*100 my feeling is values can’t change ( you can test this in Photoshop by bouncing back and forth from Adobe to sRGB you shouldn’t see a change in lightness values , but if you assign sRGB you will).





It’s true that the reproduction curve of sRGB is weird to say the least, I think it’s a hybrid of 1.8 and 2.2 but if the file is being converted and not assigned, I beleive the L*values are being translated accurately , ( this would mean the 2.2 contrast curve is being translated into the sRGB curve respecting their original values. As long as we don’t adjust the file in sRGB we should be ok.





However in light of this information I’ll be spending the next few days testing.





Eugene

















De : QuadtoneRIP@yahoogroups.com [mailto:QuadtoneRIP@yahoogroups.com]
Envoyé : July-30-16 10:36 PM
À : QuadtoneRIP@yahoogroups.com
Objet : [QuadtoneRIP] Re: QIDF versus ICC








It is my understanding that Adobe has changed the colour management in recent versions of Photoshop in a way that also affects Windows users.  This change is not that well known, and fortunately for this forum, it doesn't affect QTR printing on Windows.


If you print direct from PS and select "printer manages colour" in the PS print dialog, then you will get a silent profile conversion to sRGB en route to the printer driver.  This behaviour is spelt out and defended by Adobe engineer Dave Polaschek in the comments section of this article on TOP:
http://theonlinephotographer.typepad.com/the_online_photographer/2015/10/photoshop-vs-printer-managed-color-printing.html


He also discusses the behaviour in OS X.  This is the only place I know where an Adobe engineer has discussed this issue publicly, although be warned you will need to read his comments (there are several comment blocks from him) many times to understand fully.





So on Windows, the people who are particularly affected are ABW users, and the users of certain RIPs that install as a printer driver, e.g. PrintFab, as these workflows use the "printer manages colour" setting.  The workarounds are either to assign to sRGB before printing, a clumsy workflow, or to do a null profile conversion in the print dialog, e.g. from AdobeRGB to AdobeRGB.  Photoshop shows a warning about this, but it still works on Windows.  Dave Polaschek warns that it may stop working one day.





I've tested this.  I ABW printed and measured the 21x4 twice - once as it is supplied as an untagged greyscale image, and once after converting it to AdobeRGB and then assigning to sRGB.  They weren't the same.  The measurements of the untagged greyscale print were decidedly odd.






---In QuadtoneRIP@yahoogroups.com, <info@...> wrote :


Paul





Thanks for the reference.





SO I will assume that ... windows users are unaffected.








De : QuadtoneRIP@yahoogroups.com [mailto:QuadtoneRIP@yahoogroups.com]
Envoyé : July-30-16 1:04 PM
À : QTR-Forum
Objet : Re: [QuadtoneRIP] Re: QIDF versus ICC








In Windows 7 I can print from Photoshop CC using "No Color Adjustment" in the Epson driver and inserting an ICC in the Photoshop Print screen.  See, for example, page 3 of http://www.paulroark.com/BW-Info/Glossy-Carbon-Variable-Tone.pdf.





Likewise, I can use an ICC with ABW printing from PS CC in Windows 7.





I believe there was a past PS and/or Windows version that did impose constraints, but my current Windows 7, PS CC setup has the settings that I need for making and using ICCs without any work-around.