Curious about ICC

Question

Mainly what do they do? As I understand, they keep the colors of the image consistent across any application you're displaying them in, is that correct?

I'm running actions and it's one of the options to batch process my photos. There's also an option for sRGB, should I have that checked as well?

I do recall way back when I noticed my images weren't the same in different programs and browsers, but don't recall if ICC was checked or not.

(If it does keep colors consistent, why WOULDN'T anyone want it?)

Thanks

davescm · Accepted Answer

HiGreat question.In digital imaging each pixel is described by some number values - so, in RGB mode, a pixel might have the following values Red 130, Green 25 and Blue 86. The problem is that the colour described by those values could vary. So they are made to describe a specific colour by putting them in the context of a colour space. So those same values will describe a different colour in sRGB, Adobe RGB, ProPhoto etc. So step one is to ensure the document has an ICC colour profile embedded, in order that the values can describe a specific colour..Job done? Well not yet. If those values, in the context of a colour space are sent direct to a screen then each screen will display them differently, depending on the type of screen and how the screen controls are set. Just walk into your local TV store to see examples of that. So we also need a description of how colours are displayed by that screen. This is the monitor ICC profile and is usually made by a hardware device along with specialist software.Job done now? Again , not quite. Our software needs to convert the colours values in the document to the colour values sent to the screen. This is the job of the colour management system. It uses the document ICC profile and the screen ICC profile and converts the values without you doing a thing. Applications that use colour management in this way are described as colour managed and include Photoshop and some web browsers.As long as you embed the colour profile in your document, anyone using a colour managed system, with a correctly profiled monitor, will view the colours correctly.So what happens when you send an image to the big wide world? Well for those who care about colour and are using colour managed software they will view your image correctly, provided you embed the profile in the document. For those who do not care, or use colour managed software, they will see incorrect colours - however the usual advice when sending images to the web is to convert the document to sRGB and embed the profile. sRGB will look close to correct on a standard monitor.What about printing? In the same way as the colour management system converts the colours to the screen, if given an accurate ICC profile describing your printer/paper and ink combination it will adjust the values so that they will print as accurately as possible on your printer (given the limitations of inks).I hope that helpsDave

c.pfaffenbichler · Answer

Mainly what do they do?If you mean ICC-profiles then they allocate actual colors to values of RGB/CMYK. If people say a color has certain RGB or CMYK values that statement is ambiguous and only by also declaring the Color Space can a definite appearance be derived. One can draw analogies to maps for example … Take a map – you can tell if place A is farther from place B or place C but unless you know the scale you cannot tell the actual distance. So you can tell if one pixel is lighter or darker or more red or more green etc. than another pixel in an image but unless the color space is declared there is unclear what the actual appearance should be. (If it does keep colors consistent, why WOULDN'T anyone want it?)Even a small profile, when embedded in thousands of files, may add up.

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