What is the purpose of embedding a color profile when saving an image?

I am using RawTherapee to process images. This program (and I suspect many others) has an option called “Working Profile”, which you can use to adjust how the image is displayed; and an other called “Output Profile”, which is the profile embedded into the image (this functionality is better explained here).

I believe I understand how color management works, and I am thus very curious why on earth you would need to save a picture with a profile. Aren’t profiles supposed to make sure the output is consistent across monitors/printers? If yes, then why would you need a separate complexity level at the point where you save the picture? Aren’t the colors simply saved as RGB hexadecimal values, which are then rendered in accordance to your monitors profile?

Similarly, if I look at the properties of my profile (in the GNOME3 settings manager) I get two very confusing tabs. One of them showing an example image looks like “if opened with the profile”, and an other one showing what the image looks like “if saved with the profile”.

I believe both these examples illustrate this point I do not yet grasp. Again, why would anybody “save” an image with a color profile?


Exactly how a color profile is stored in an image depends on the image format. In PNG, for example, it’s contained in a PNG iCCP chunk. In JPEG, it’s stored in a particular “marker”.

For other image formats, see

About the “why”, the embedded color profile tells how the image author intended it to appear. Display applications and printing software can combine the embedded image profile with the display profile to come up with the complete transformation needed for your display or printer.

If you image is in the sRGB colorspace, and it’s destined to be displayed on the web, you probably don’t need to store a color profile in the image, because the browser will assume it’s in sRGB anyhow and go from there. In fact, this is the safest course: convert your image to the sRGB colorspace and then remove any color-management metadata such as PNG sRGB, cHRM, iCCP, and gAMA chunks. Even today (April 2015), Firefox by default displays sRGB-tagged PNG images with a slight mismatch to HTML colors of other elements.

See various long documents at http://www.color.org for the gruesome details, and https://bugzilla.mozilla.org/show_bug.cgi?id=621474 for a 4-year-old bug report on how Firefox handles sRGB-tagged images.

Source : Link , Question Author : TheChymera , Answer Author : Glenn Randers-Pehrson

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