Mar 182011

Profiles are a part of the method for conversion between varying colour spaces.

For example, while viewing a CMYK file on a monitor (an RGB device), there is no direct link between RGB and CMYK colours. There needs to be a translation in the middle that allows this to happen (cielab) plus a description of how these colours should look. Different RGB devices will produce colour differently to each other, and be different to other RGB devices like scanners or digital cameras. Likewise, CMYK will produce colour differently on different devices and media. Each specific output requires a description of how to accurately produce the colour in a digital file.

There are always 2 profiles in any conversion (with the exception of files created in cielab). There is an “Input or Reference” profile that describes what the file should look like, and an “Output or Media” profile that explains how to achieve that result. In between these two profiles is cielab to allow this conversion to happen.

A profile is a table that communicates colour. An example of this is a CMYK media profile for a printer, this would offer information as follows: “CieLab–>CMYK”. On it’s own it does not give enough information to complete the action. If you were using a RGB file then there would also be an RGB profile in use, and the full conversion would show as follows:

RGB –> CieLab –> CMYK

This conversion might actually be as follows in colour values for each conversion:

R=255 / G=0 / B=0    –>    L=54 / A=81 / B=70    –>    C=0 / M=99 / Y=100 / K=0

You can try this yourself in Adobe Photoshop: Create a new blank page and use the “Color Picker” tool. Enter 255 in the RGB “R” area and leave G&B as 0. You can see the different values across the spaces all in one screen.

“Screen grab taken from Adobe Photoshop”

Results will vary depending on the profiles you have selected in your Photoshop “Color Settings” area as your working spaces (you can view this by pressing Ctrl-Shift-K from Photoshop).

“Screen grab taken from Adobe Photoshop”

This also demonstrates the importance in your choice of colour settings even just while working on files in your design packages.

Compare profile creation equipment and software at cielab colourshop


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