Re: PS vs. Acrobat printing

tacit wrote: 
In article <NpGdnXSHn68HDyjenZ2dnUVZ_sadnZ2d@xxxxxxxxxxx>,
 John McWilliams <jpmcw@xxxxxxxxxxx> wrote:


Thanks, T, what I was going to say insofar as what the printer told me. I made every effort to put all my images into grayscale before I imported them, unlike my first effort where I had to go back and convert quite a few.

The cover has a slight color cast to it, and it was run on a four color press, no doubt, even though it's all B + W.


Did you tell your printing shop to run the cover in four colors? Did they charge you for 4/C printing? Was that your goal?

No, no, and no! We had no ads paid for in color, and I suggested saving a few hundred by making it all B+W. I suspect the printer used a different press for the cover as it was heavier stock and they are used to doing color covers a lot.

You can print a grayscale image in CMYK on a printing press, and there are advantages to doing so. The results can be quite breathtaking, with good contrast and very high detail (especially in shadows). But there's a price to pay. Printing a 4/C grayscale image on press without intruducing a color cast is something of an art, and it's not easy to do. The press operator can adjust the color cast, to some degree, but getting a truly neutral 4/C grayscale is quite difficult.

Makes total sense to me. It was possibly their oversight that they used CYMK where they needn't/shouldn't have.


I am trying to redetermine what happens, and from trying to decipher the quantities of info available in the Preflighter in Acrobat 6. It still looks like the images are in "Separation Color Space (Black)", but perhaps the fonts are in CYMK. (?). It shows that some "images" (presuming they treat the fonts as such) are in four plates.


Images are pictures. In a PDF, vector type is not considered an "image." If you have images on all four plates, that suggests that (1) the original images are not grayscale (they are RGB or CMYK), or (2) the job settings that were used to create the PDF are wrong.

I'd lean heavily towards (2). My responsibility in any event, and, now rechecking the custom set I made, I am appalled to see that it's set to convert to CYMK.... although I had made a subsequent one to leave color unchanged. So, you hit another nail square on.

You can instruct Acrobat to perform color management, to tag images with color profiles, or to convert images from the original color model to some other color model such as CMYK. Unless you have profiled your system, you know what you are doing, and your printer has given you color profiles for his press, it is important to set up your job options so that Acrobat does not change the colors of your images. This means not assigning color profiles, converting to profiles, or changing the image mode. 

Looks like I blew it on that, although I would have sworn I did not do
that- but there are no human gremlins around who snuck into my machine....

I guess it might be easier to just turn over the InDesign files rather than make all new PDFs? Are the IDesign files inherently better for commercial press?


Well, not necessarily. A properly prepared PDF is absolutely perfect for commercial printing--the devil, though, is in the details. A PDF not prepared in the right way with the right job settings can create all kinds of problems.


Yes, I am now a Believer. Exporting a new PDF with a new preset [that doesn't change the grayscale images to CYMK] (!) now makes the two appear the same on the screen, and the printing proofs on bright white paper look much closer to each other. When printing from Acrobat, there's no apparent way to turn off Epson color management when printing to plain paper...

They sure as heck are easier to proof on my little inkjet, and their losing of contrast when I convert to PDF is still a mystery, although it occurs to me that I haven't been paying enough attention to my proofing space. What should it be for grayscale images?


Are you using color profiles on your computer? Have you profiled your system? If not, then make sure you're not inadvertently doing any color management in the PDF.

My Mac (G5)'s LaCie tube is profiled via Spyder, and I get good matches out of PS printing using CS color management, color management turned off in the Epson R300 drivers, using the built in Profiles for various Epson papers (plus Gallerie smooth Pearl, but i don't proof with that.)

The color management you speak of would take place in the Export function of InDesign, no? If not, I'll need to dig deeper into Acrobat's settings to see what I can do, but right now the differences are so small that it may be due to the print driver. (?)

--
John McWilliams




.

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