The Colour Challenge
RGB vs CMYK
Additive and subtractive colours
Colour Management for the Layman...
Broken colour management
Process colour was invented over 100 years ago as a method of creating acceptable 'full colour' from 3 primary colours and black. (CMYK, cyan-magenta-yellow and black, K stands for Key or black. In the old days, the black was printed first to provide a registration key for the other colours)
The problem with cyan, magenta and yellow, is that when they are mixed, they make black or shades of grey. This is why you can't print the same colours you see in a transparency or monitor, they are comprised of red, green and blue light, which makes white when mixed in equal proportions. These are known as Additive and Subtractive Primaries respectively.
There seems to be a lot of bad colour management going around....so what colour ARE the sunflowers anyhow?!?
The image at left includes a sampling of reproductions of a famous painting, there is a reason that they are all different... ignorance or indifference towards colour management.
Sadly, most people assume that if colours on their monitor look okay then the print will be okay, they trust that an image supplied to them will be the correct colour and that when they include the image in their print file, it will reproduce correctly.
To control colour, there is a complicated process called Colour Management.
Colour Management requires each stage to include colour profiles to allow correct conversion of the file for each device or process that it passes through, including colour adjustment in Photoshop, placement in InDesign, output to PDF, all of these stages and more require correct settings and the default settings are not the correct settings!
When a file, such as a .psd image or a .tif scanned image is created or saved, it must have a Colour Profile embedded in it so that subsequent processes can set the correct conversion. When saving a file, look in the options on the save dialogue for an option to 'Embed Profile".
The best way to imagine how this works is to imagine this analogy below...
The Postcard Analogy....
A layman's explanation of colour management
Don't feel bad if you don't understand colour management, ...you are not alone!
I am using colour management successfully on a daily basis in an average printshop. Here I will share my understanding of this vital process...
The Postcard Analogy.
Each file that arrives at our factory can be imagined to be a postcard from some foreign land and the colour profile can be thought of as the stamp on it.
It might be written in Spanish or it may be in Portuguese, and you need to translate it into English before printing; but unless you speak 300 languages you would not know which translation dictionary to pull out.
Ah-ha, look at the postmark! It has 'Espana' on it, so we will translate with Spanish as the source language.... Using a Spanish-English translation dictionary, we can translate the file into english, and you will get a good translation of the meaning of the message.
So now imagine that a tiff file is a postcard and the colour profile saved with it is the postmark. This profile defines the origin of the colour space ( the language) within the file and allows our software to translate the information into our native colour space.
That is the basis of colour management.
The same translation happens many times in the active life of that file....
When the file is accessed by the layout application (InDesign colour management on)
When colour adjustments or corrections are made in Photoshop (Photoshop CMS on)
Output to PDF for imposition (InDesign export settings)
Ripping file for proofing (Proofer colour management on)
Press density settings (to industry colour management standards)
Each application that accesses the file has a native colour space or language that it uses.
Part 2.....missing profiles
If a file is saved without a colour profile, it is like the postcard without a postmark....you might guess the right one, but its hard to pick spanish from portuguese....best to call the originator and ask them what the correct working space would be. If they say they don't know, you had better encourage them to learn about colour management too! Then maybe next time, they will embed a profile and you will both be much wiser.
If colour management settings are incorrect, or if images are saved without colour profiles being embedded, then the colour is random.
Imagine that the postcard from Spain was translated using a German-English dictionary!
The outcome would be gibberish.
That is what happens to a lot of printing.
If you are unsure about whether your workflow is correct, please feel free to contact us for help.
Click tab: Part 1