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|| SportsShooter.com: Member Message Board
CMYK conversions
Michael Troutman, Photographer
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Carmel | CA | USA | Posted: 11:43 PM on 09.17.09 |
->> For those doing CMYK conversions for publication: are you leaving Black Point Compensation checked or unchecked? And are you leaving intent set to Relative Colorimetric? It looks better to me on-screen (fully calibrated, of course) with Compensation unchecked, but I'm wondering how that looks after four color printing.
This is primarily for magazines and brochures. I shoot/process everything in Adobe RGB and convert to CMYK (if asked) as the final step. Have previously just used Adobe's defaults and not given it much thought. But I'm using a high-ISO D3 file for an ad (with lots of black shadows and neon colors) and noticed a dramatic change when converting to CMYK. Unchecking the Black Point Compensation helped, but the colors were still flat. I'm mostly worried about the blacks going grayish or "muddy". But I'm getting the impression that what you see on the monitor in CMYK is not what you get in print (unless you load special CMYK profiles from your printer). So just close your eyes and hope?
Apparently there's not much that can be done about neon colors losing their "pop" in CMYK. It is discussed in this thread here: http://www.sportsshooter.com/message_display.html?tid=19967
I realize this is actually a huge subject with no easy answers, and there are a lot of variables between presses, but any technical insights/comments are appreciated, especially about not using Black Point Compensation. And yes, I'm going to have a long technical chat with the printer tomorrow. |
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Michael Troutman, Photographer
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Neil Turner, Photographer
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Bournemouth | UK | United Kingdom | Posted: 4:19 AM on 09.18.09 |
->> When I did my pre-press course a few years back the guy leading the course said that (if he had time) he would often try an image in relative colorimetric first and then have a look at it in absolute and go with whichever allowed the file to retain it's "essence". Some image rely on a specific colour for their impact (sports clothing for example) and others need a spread of tones (90% of portraits) to work well.
Newspapers tend to use cheap inksets and have high levels of dot gain and so need to be treated entirely differently from quality magazines with good ink and good paper.
The Adobe link shows you how to get your monitor to preview images as well as it can be done on a decent monitor and that is always a good place to start but experience is king here - getting used to the differences between what you see on screen and what you see on the page. Having the skills to allow for those differences is what matters in the end. |
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David Harpe, Photographer
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Louisville | KY | USA | Posted: 7:42 AM on 09.18.09 |
->> If they're a decent printer they should have a prepress department with people who prep stuff for their presses every day. They would be the ones to talk you through the setup.
Black point compensation is only one small variable when it comes to how your blacks will look on press. GCR vs. UCR, dot gain and total ink coverage are key variables as well.
http://graphics.tech.uh.edu/student_work/color_rendering_intent/gcr.html
Note that in the above description they use the "Custom" CMYK profile to get to all of the settings. Also note that all of these settings are specific to the type of press being used, the type of ink and the type of paper. That's why a good collaboration with your printer is a must.
I did a 230-page book where 90% of my photos were full-page spreads of very colorful glass sculptures - a difficult printing job. The printing was done on a press in China, so press proofing was expensive and difficult (we only got two shots at it). Getting the color correct was a bit tricky because we were using an ink and paper setup that was not typical for the printer - hexachrome inks and really high quality paper.
The domestic contact for the printer had a printer profile for an Epson 9800 that was fairly closely matched to the press in China. This is how they would do proofs domestically before sending jobs to the press. They gave me a copy of that profile so I could use it on my 9800. The proofs from their profile were close to the first proof, but not spot-on. I was able to come up with an adjustment curve to more closely match the first round of proofs. This was very useful and allowed us to tweak things and experiment before the second round of proofs. Color-wise the second round of proofs were nearly a perfect match to what we'd proofed on my 9800, and the final print run was gorgeous.
Saying "GO" on a 20,000 copy press run of a 230-page book being printed overseas with over 400 files that you hand tweaked with a customized printing profile was intense. Talk about pressure! |
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Mark Loundy, Photo Editor
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San Jose | CA | USA | Posted: 12:35 AM on 09.19.09 |
->> Michael,
Is this for pieces that you are producing yourself and working directly with the printer? If so, they can tell you what their press requirements are.
If you're not working directly with the printer, you should not be doing CMYK conversion at all.
--Mark |
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Fj Hughes, Photographer, Assistant
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Baltimore | MD | USA | Posted: 8:47 PM on 09.20.09 |
| ->> Jeff Schewe recommends leaving black point compensation checked. I have always followed this recommendation. |
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Mark Loundy, Photo Editor
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San Jose | CA | USA | Posted: 10:29 AM on 09.21.09 |
->> Black point compensation is there for a reason. Repeating: CMYK conversion settings are specific to an individual press operation. Some will need it, others will not.
--Mark |
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Tom Ewart, Photographer
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Bentonville | AR | USA | Posted: 11:09 PM on 09.21.09 |
| ->> I did photography, production & prepress for 4 color DTP Magazine for several years and I have to agree with Mr. Loundy's advice, unless you are doing the prepress and understand what exactly what you are doing in close concert and with instruction from the press guys, it's best left to others who. It is specific to the output device it's best left in the hands of production and prepress people. And yes images do loose a lot going from RGB to CMKY because the color gammut is much smaller--there are lots of colors we can get in RGB we can't reproduce with presses loaded with process color inks. |
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