Need help concerning Black generation…….

MF
Posted By
Mickeal_Farris
May 10, 2005
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1317
Replies
14
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Closed
Hi guys,

I’m having problems with my book cover images that I’m creating in Photoshop. My cmyk profile is set to "SWOP COATED" for ink colors, medium for black generation, 85% for black ink limit, and 240% for total ink limit. It seems that when I create a cover that has a lot of black or dark areas in it, the final print output shows almost a flat black or gray in those areas, making the image look low-resolution. The image looks fine on my monitor. I import it into indesign cs and generate the pdf file that I send to the printer. I have indesign set up to use the same cmyk profile as Photoshop. The pdf file looks just fine as well. Yet when I get the printed book cover from them, it looks less than desirable. Does anyone have any suggestions on what the problem might be? It’s hard to figure out when what you see looks fine.

Thanks
Mike
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LH
Lawrence_Hudetz
May 11, 2005
Do you get a Match Print before going on the press?
MF
Mickeal_Farris
May 11, 2005
Hi Lawrence,

Thanks for the response. I have done a match print, but I’m not sure how much use I can get out of it since I only have a HP inkjet printer. It does appear though that the black and other dark areas on the match print are normal in relation to the rest of the image. There’s nothing on it that would indicate the image would turn out the way it does after it comes back from press.

Miike
LH
Lawrence_Hudetz
May 11, 2005
Well, at this point, I would definitely have conversation with the printer.

You might also bring the Match Print. An accurate one needs to be made to the particular press on which which you are going to print. If you did it with your HP, it probably won’t match.

You might want to go on to the InDesign forum with this question as well, as these folks have much experience with such things.

If John Levine checks in here, he would have a lot to say. (nothing like putting John on the spot, ‘eh?)
MF
Mickeal_Farris
May 11, 2005
I’ll do that.

Thanks again.
GH
Gernot_Hoffmann
May 11, 2005
Mickeal,

total ink limit 240% is too low for coated – should be 300% or 320%. About black ink limit by Dan Margulis, Professional Photoshop: ‘I recommend an 85% maximum for virtually all print conditions. Anything between 75% and 90% makes sense. Photoshops default black ink limit 100% is a recipe for mud.’
I didn’ get mud for rich black grayscale and color images, using ISO Coated, which has IMO either 95% or 100% (not sure about).

Best regards –Gernot Hoffmann
P
Pipkin
May 11, 2005
That is. Even 350% total ink for glossy paper (240% fits rough newspapers). And pay attention for dot gain in CMYK settings. (15-20% for quality paper is the best, 30-35% for rough paper). IMHO.

* Better would consult your printing-house for exact settings.
GH
Gernot_Hoffmann
May 11, 2005
Pipkin,

more than 320% total ink limit doesn’t increase the density remarkably, but problems may arise for drying.
15%-20% dot gain is probably OK, but the dot gain settings belong already to the profile for CMYK (opposed to Grayscale, where dot gain has to be set explicitly).

Best regards –Gernot Hoffmann
MF
Mickeal_Farris
May 11, 2005
Hi Gernot,

Thanks for the response. Let me preface this by saying that I am a newcomer to Photoshop, so to say that I’ve been frustrated with some of the print results I’ve gotten would be a vast understatement.

One of the first problems that I had was I received a cover back from my printer (Lightningsource, by the way) where they complained of the black being a “registration” black (100C, 100M, 100Y, 100K) instead of a rich black. Their message said they require black to be built from 60C, 40M, 40Y, 100K. And I believe the actual error message that they received from the actual printer was something to the effect “total ink density cannot exceed 240%”. This prompted me to put the total ink limit to 240%. I’m not sure if that is correct or not. Whenever I build a cover from scratch, I don’t seem to have a problem. If I place a black background or black text on a cover, I use 60,40,40,100, and it prints out fine. Looks like a real black. My problem lies when I receive an RGB image from an author and have to convert to CMYK. The black seems to “go light on me”, almost to a flat black or gray. What settings in my CMYK profile would affect this? Black ink limit? Black generation? Will lowering the black ink limit to say 70% make my black look richer? Or do I need to raise it? My black generation is set to medium. Should that be changed? Are there any other settings in my CMYK profile that could be affecting this? Sorry for the length, but any help would be greatly appreciated.

Mike
GH
Gernot_Hoffmann
May 11, 2005
Mickeal,

this is the same link as in the InDesign forum:
< http://www.digitalmastery.com/companionsite/book/Custom%20CM YK.pdf>

This doc says clearly: total ink limit on Coated: >=300%.

For black areas on a cover it would be sufficient to add some cyan to the black, but the recommendation 60-40-40-100 is OK as well. Small black text on white is normally K-only.

The sum 240% is not valid for images. Here we have only small very dark areas. Then use up to 320% total ink.

Practically you should ask your printer which profile he expects. In Europe ISO Coated, in other countries eventually SWOP. IMO, there is nothing to tweak. The only exception is an unusual medium, let’s say a yellowish paper or a heavily coated paper.

Expert’s knowledge like Dan Margulis’ advice (e.g. use light GCR instead of medium GCR, depending on the image content) cannot be easily put into practice by ‘the layman’.

The standard profiles guarantee an average good result.

I would check the RGB-CMYK conversion, either by converting the image or by a soft proof. Then measure the ink values in dark areas.

Best regards –Gernot Hoffmann
MF
Mickeal_Farris
May 12, 2005
Thanks Gernot.
IN
ivan_n_petrov
May 12, 2005
hi michael,
print your picture, calibrate your monitor – using for monitor rgb – adobe gama- adobe rgb 98 – the print result must look like that you see at the monitor – your question is vise versa – the cmyk profile you use lightness the picture and made it gray – you print liht image and you recieve the same – the levels in the rgm model are different that in the cmyk – the histogram turns 180 degrees
IN
ivan_n_petrov
May 13, 2005
Calibrate your monitor to the print result – using the adobe gamma or the monitor. Use Adobe RGB!!!, gama 1.8 or 2.2 – they are different but good – deppends of your monitor. You see black instead gray – 66c-56m- 56y- 70b or ???? is good for newspaper but not for coated paper – a black 67- 60- 60- 86(90) is good for it. You must print a proof to calibrate exactly the monitor – what you see on the paper – that mustyou see on the monitor –
IN
ivan_n_petrov
May 13, 2005
Calibrate your monitor to the print result – using the adobe gamma or the monitor. Use Adobe RGB!!!, gama 1.8 or 2.2 – they are different but good – deppends of your monitor. You see black instead gray – 66c-56m- 56y- 70b or ???? is good for newspaper but not for coated paper – a black 67- 60- 60- 86(90) is good for it. You must print a proof to calibrate exactly the monitor – what you see on the paper – that mustyou see on the monitor.
PF
Peter_Figen
May 13, 2005
The first thing to determine is the type of press and the type of paper being printed on. That will set you in the right direction in terms of ink density. The above advise has pretty much been good with the exception of the calibration advice in post #11.

If you’re printing on a coated glossy stock, then an ink limit between 280 and 310 is going to be fine, and most printers can accommodate if you’re a few points off. The age and conditon of the press, and the speed (impressions per hour) at which the printer typically runs will drastically affect the optimum settings. I’ve also found that many printers are overly optimistic in how much ink density they recommend. I’d much rather be 10 or 15 points low in my file and have then push the densities than the other way around. Again, image content can dictate also.

The biggest problem is that you’re in a bit over your head in a swamp that is full of crocodiles just waiting. As you have seen in a few short messages here, there are many, many facets of getting a good print job done.

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