Friday, January 6, 2017

Converting CMYK values to RGB and hex values. Is there a best practice?

This query came via email

Color Management

Looking for some advice when converting CMYK values to RGB and hex values. Is there a best practice? Obviously there are several different ways to get numbers but they don't all give you the same answers. Any ideas?


“Is their a best practice?”

Color management in my studio work flow started with color calibrating, creating ICC profiles of all the tools. A spectrophotometer is the tool that will do all you need in your studio. With this you create ICC profiles of your monitor, scanner, camera, printer & papers, all these input and output devices you use. You have to keep these different kinds of profiles current.  Big part of CM is be consistent in updating ICC profiles and then creating project files. The goal is take control and to match the colors of the image displayed on your monitor with the ones produced by your in-house printers and all outside print venders.

The question of going from CMYK to RGB is a workflow practice choice. At times the choice is not given.

CMYK to RGB

This is not a good practice the color space of CMYK file is different and smaller then a RGB larger color space. So going CMYK to RGB you have gaps. The color gamut of the computer screen and CMYK file gamut may not make an accurate translation. The converted CMYK image may look unsaturated.

This is a best practice.

An original file with RGB profile becomes the master, the converted to cmyk version or even a SRGB version a child.

Industry standard is use ICC profiles and an RGB-centric workflow. In this best practice model, source artwork stays in a large, standard RGB working space for as long as possible. All color corrections are performed in this space, converting color only when targeting for various final outputs that may include websites, high-quality inkjet printing, and printing on press.

So when you can not get that master-RGB file, and you have to convert CMYK to RGB.

Use the “convert to profile” under the edit menu technique.
The best you can do is control your product, your art-file output, so calibrate, profile equipment, tag your files, practice consistent workflow in your work.
 

Worst case when no icc profile exist in the cmyk file you have to convert.

Untagged CMYK file, go ahead use “convert to profile” technique. Next make corrections as needed, then make a proof print. Meet with and explain situation, and have client sign approval on the proofed color print.
Your work is still better then those that don't use CM and tag their files. When you practice good CM you know that what you see on your monitor is accurate.
Those that don’t practice color management are just cutting overripe tomatoes with a dull butter knife.

Great information and resources here:

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