Which conversion process produces better results – RGB to CMYK or the other way around?

Question

I've thought about this question for so long but I couldn't think of a good way to phrase it to be searchable. So I decided to ask you guys, and I apologize if it's a repeated question.

If I'm working on a document in Photoshop and I'm planning on displaying this design digitally and in print.

What's better in this case, to create the document in RGB and convert the finished design to CMYK for print, or the other way around?

I'm primarily concerned with which process will cause less damage to the design colors or quality overall?

Answer 1

I always start in RGB in Photoshop, and generally in CMYK for Illustrator.

RGB for Photoshop so I have access to all functions and tools. I switch to CMYK when ready for press as the final step.. then check colors and adjust if needed.

CMYK for Illustrator, because I'm old school and if I'm working In AI, and something needs to go to the web, I copy/paste to Photoshop (RGB) and save it for the web. To me, Photoshop has always been better for web images.

I don't know that one is absolutely "better" than the other. It's more a matter of workflow preference than anything.

Answer 2

I think it depends where the majority of the viewers will be seeing it, because starting in RGB and then converting to CMYK can result in certain colors appearing dull or desaturated. If you start in CMYK and then convert to RGB, you will be limiting your available color palette for those viewers who will be viewing on a screen.

If the majority will be viewing online - work in RGB

If the majority will be viewing in print - work in CMYK

Answer 3

I assume by "working on a document" you mean "painting" your own picture from scratch in Photoshop and not color correcting a photography.

If that is the case you have two options:

1. Work in RGB (and maybe convert to CMYK for print later)
2. Work in CMYK

I recommend working in RGB.

RGB is the "natural" way of working with colors digitally. It is based on the way colored light mixes additively. CMYK is an invention made for printing on paper, normally involving some kind of screening. It is based on the way dots of the four CMYK colors mix subtractively.

When converting an RGB image to CMYK you are asking Photoshop to make that CMYK version of your image which would give the best possible representation of your image on a specific kind of paper and on a specific kind of printer/printing press.

Painting or manipulating images in CMYK makes color profiles lose their purpose so you are on your own trying to predict the final color. It should only be done if you know exactly what you are doing regarding dot gain, total ink etc.

For example if you convert an image from RGB to CMYK and then add a lot of contrast because you want the image to be dark, the amount of total ink on the paper could become too high. During printing process the printer could be forced to apply a little less color to avoid the papers from "gluing" together resulting in a lighter print. The opposite of the desired. The contrast should have been added in RGB before converting to CMYK.

I recommend you work in RGB (for example Adobe RGB). You will have access to a lot more filters and effects and layers will blend more smoothly than in CMYK. The problem is that you can easily pick colors that would not be possible to print. All the bright colors look very differently when converted to CMYK.

Photoshop gives the possibility to preview how the image would look if it was converted to CMYK:

1. In "Edit/Color Settings", make sure that you have chosen an appropriate CMYK profile. Get it from the print shop or printing press you are using or just choose something standard like "Coated FOGRA39".
2. In "View/Proof Setup", make sure "Working CMYK" is checked.
3. Make sure "View/Proof Colors" is checked.

Now you see the exact same image as you would see if you converted the image to Working CMYK. You can work with it turned on all the time or just tick it on and off to check once in a while. If it is not obvious enough which colors have changed you can turn on "View/Gamut Warning" to show the colors that can not be reproduced with CMYK marked in gray.

When you are done with the image you can make a low res sRGB jpg for the web and a high res tif/psd for printing. You should ask the print shop / printing press which color profile they prefer. Maybe they just want to have the RGB version and do the conversion themselves or let the printer do the conversion.

Answer 4

In terms of gamut, CMYK is completely subsumed by RGB: there are no colors that are in CMYK that are not in RGB, so converting to RGB is less destructive. I have done a lot of work in print that uses photographs of artifacts and paintings where the goal is to color-match the printed version to the actual object. We then use the imagery online.

For me, I have found that for the photography, working in CMYK as early as possible allows me to get to the color right without worrying about a destructive gamut change from RGB to CMYK. I shoot in RAW, run my preset curves, open in RGB and immediately convert to CMYK before even looking at the object for comparison.

If you are working with photography and have reasonable monitor calibration for CMYK work, then if it looks good in print and on screen, you will be able to preserve that look in RGB with little to no tinkering. If you have some you want to boost saturation (etc), you can relink those to an RGB version.

In the case of inDesign and any program that stores a swatch index (instead of a color) on an object, take your list of swatches (e.g. brand-affirmed list of colors) and make two sets, one for CMYK, one for RGB.

If your program uses the names given, you can probably overwrite one set with the other by simply using the same names. If not, you can probably remove one swatch and replace all instances of it with another of your choosing. In this example you'd remove the brandBlueCMYK swatch and assign brandBlueRGB as its replacement. Because you are working with a swatch, this change will propagate through the whole document.

The photos will be unaffected, and you now have a quick way of altering the document for RGB output that preserves your photography color adjustments.

For photos, if you make cmky and rgb folders and then use the exact same names in both branches, then relinking from CMYK to RGB is as simple as renaming the CMYK parent folder, opening the document, then re-freshing the links by pointing to the RGB folder.