Understanding Image Color Profiles

An image file stores pixel values, and it can also declare which colour space those values should be read in. If the two do not match, a perfectly good image can look washed out, too saturated or slightly off once it leaves the program that made it.

sRGB: the web's default assumption

Web browsers assume an image is sRGB unless it says otherwise, and for most web and social-media images that is correct, because sRGB is the standard colour space for screens. That is why trouble tends to appear with files that are not sRGB.

CMYK: built for print

Design programs exporting for print often use CMYK, a colour space modelled on ink on paper rather than light. A browser that treats a CMYK image as if it were sRGB can show dull or shifted colours. The image is not damaged; it is being read in the wrong space. JPG and TIFF are the formats where CMYK is most often met.

Adobe RGB and other wide-gamut profiles

Some cameras and photographers use Adobe RGB or similar profiles, which can represent more colours than sRGB. Shown with the profile respected, that is a benefit. Shown by software that ignores the profile, the same numbers look more saturated or shifted, because the pixel values mean something different in a wider space.

"Untagged" files

Some files carry no profile at all. Most software, browsers included, then assumes sRGB. That is usually a good guess for ordinary web photos, but it is a guess, especially for a file that began in a print or wide-gamut workflow and lost its profile on the way.

What this site's tools do with profiles

This matters when you convert or compress a profiled image:

• The Image Metadata Remover keeps the embedded profile on purpose, because removing it can change how colours look.
• The tools that re-save a picture, such as the compressors, the Image Resizer, Image Cropper and rotators, do not carry the profile into the result and do not convert the colours first. An image in a wide-gamut profile can therefore look different afterwards, because the same numbers are now read as sRGB.
• The TIFF to JPG converter converts to sRGB and does not embed a profile in the JPG. In our test, a CMYK TIFF made from an RGB image gave the same colour at the sampled pixel; a real print-profile file can still shift slightly.

The safe way to handle a wide-gamut or CMYK image for the web is to convert it to sRGB in the program that made it, then use these tools on the sRGB version.

A routine for web images

1. Check the file's profile before you do anything else (see below).
2. If it is not sRGB, convert it to sRGB in your editor. Converting changes the pixel values so the colours stay the same. Assigning a profile only changes the label and shifts the colours, so it is the wrong choice here.
3. Export as JPG, PNG or WebP. Embedding the sRGB profile or leaving it out both work on the web, because browsers assume sRGB.
4. Only then use resizers, compressors and converters, and compare the result with the original on a normal screen.

Checking a file

Instead of judging by how a picture looks in one program, the Image Color Profile Checker reports a file's actual colour space, whether it carries an embedded profile, the profile's name if present, and its bit depth. It is a diagnostic only and does not convert anything. To fix an off-profile image, re-export it as sRGB from the original software and check the result with the same tool. See also JPG vs PNG vs WebP for which formats can carry a profile at all.