RGB to CMYK conversion -- more than one way?

Question

Occasionally a science journal asks authors to submit figures as CMYK (JPG or TIFF) for publication. When I have done this in the past, the colors in the figures end up looking very muted and washed out - even when published in print format. What I don't understand is that these same journals have published articles from others where the figures are nice and vibrant both in print and online in PDFs.

My question is whether there is more than one way to convert RGB color to CMYK. The tools that I have tried (Adobe acrobat, Adobe Illustrator, Deneba Canvas, Apple Preview) all produce the same muddy images.

Is CMYK actually too restrictive of a color space for modern printers? Doesn't it presume that there are only 4 colors of ink in the printer?

I'm guessing that other authors have ignored the publishers request, and have submitted their figures in RGB or some other expanded color space; perhaps the publishers hardware are capable of a wider range of color than CMYK allows -- or is there more than one way to do the color conversion?

Answer 1

It is very likely that people ignore the specs and the pre-press people at the journal are making the conversions. There is a lot of information and confusion surrounding this topic, but the simple answer is: testing.

What you need is a monitor that you can trust so that what you see on screen is as close as is acceptable (to you) when printed by a printer. To know if it is close, you need to find a printer who will pull proofs for you (cheaply) so that you can do some testing. Good printers tend to calibrate to similar (or even the same) target and they are pros, so if you get it set up well with one, you will probably have decent results with many.

I have one monitor in my setup which is trustworthy. I used a monitor calibration device on it (which can be rented from camera shops), and I disable the use of embedded profiles. None of the other monitors I have, even calibrated, simulate CMYK well.

Basically, I have calibrated the monitor, and then made adjustments to the display profile in e.g. photoshop based upon printed results. This is obviously a specialized calibration.

You should be aware that CMYK vs RGB is more than just a color gamut difference: in addition to the additive/subtractive difference in the color models, CMYK tends to look flatter because it relies upon the white point of the paper which is a lot duller than the white point of a monitor.

Answer 2

Yes, there is no 'one' way to convert between the two.

What will probably help is to get the proper color profile setting from the publisher. You can then use this profile in your software to ensure a better conversion.

Ideally, though, the vendor would be handling the conversion themselves as they are ultimately the ones printing it.

Answer 3

For optimum results simple conversion is rarely enough.

It generally takes conversion to CMYk, then image adjustments to tweak the colors. This is especially true if original areas of color fall outside the CMYK gamut.