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Is conversion from one colour profile to the other other clearly defined ?

If I change the ICC profile for an image from sRGB to another profile such as Adobe RGB will it be applied the same way by all Imaging software ?

Will it be applied the same way if the printer converts the profile to one based on the CMYK Colour Space such as FOGRA27 profile as if I convert it to a FOGRA27 profile myself before sending to the printer ?

(I think that with softproofing the image can be modified as well but with just changing the profile we are just changing the mapping)

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You are confusion color model and color space. sRGB and AdobeRGB are the same color model (RGB) but are different color spaces. CMYK is a different model and in itself does not define a color-space.

The transformation between sRGB and AdobeRGB is therefore more similar but software still have leeway on how to apply it. Any color outside sRGB can be mapped differently, some software offer users options which different properties, some preserve the input as much as possible while other transform so that colors are relatively proportional. See this link for an explanation.

  • Ive fixed the question regarding colour profiles and spaces – Paul Taylor Nov 17 '15 at 18:06
  • Ah useful link but I think this is the one I needed color-management-guide.com/convert-to-profile-an-image.html I thought when you changed colour profile the RGB values didn't change but just how they mapped to LAB changed. Whereas actaully if you have the right profile to start with and then change to another profile it goes RGB - > LAB and then LAB -> new RGB and the problems arise when original RGB maps to a particular LAB value, and that LAB value isn't mapped to by RGB in the colour space, which is where they have some leeway. – Paul Taylor Nov 17 '15 at 18:27
  • But I dont see you can use perceptual/relative except when soft proofing. Because for example if I export a image as a jpeg in Lightroom I can specify the embedded profile but I don't specify how it is done, or does it literally just change the profile without actually converting the rgb vales from rgb -> lab > newrgb when I pick this option. To put it another way can I properly convert image from one profile to another at export stage or it only to be used to correctly specified the right profile in case it is currently set wrong. – Paul Taylor Nov 17 '15 at 18:29
  • Not 100% sure about LR but IIRC, it just converts without asking, so what choice it does is fixed. In theory you can and there are plenty of mappings possible. If you embed the color-profile, then it does not have to change values, otherwise, it has no choice but to produce pixels of certain values according to the mapping it uses. – Itai Nov 17 '15 at 19:28
  • sorry I dont understand what you are saying – Paul Taylor Nov 17 '15 at 20:56
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There are four rendering options for converting color spaces. Two are of interest to photographers. These options instruct the software how to deal with out of gamut colors. Once an images is rendered to a smaller color space you can go back to a larger colors space but you cannot undo the rendering to get the same picture back.

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