Editor › Learn › Gamut Explained: What Your Device Can and Cannot Reproduce
What is a colour gamut?
A gamut is the complete set of colours a device or colour space can reproduce. Displays and presses have different, partially overlapping gamuts: a screen reaches saturated colours no press can print, and a press produces some inky cyans that common screen spaces clip. A colour outside the destination gamut cannot be reproduced there — a conversion must remap it, and the rendering intent decides how.
Gamuts are volumes, not lists
Every reproduction device — a display, a press, a photo printer — responds to a limited range of stimuli, so the colours it can produce form a bounded three-dimensional region in a colour space such as CIELAB: lightness in one axis, the two opponent colour axes in the others. The familiar flat "gamut diagrams" are slices or projections of that volume, which is why two gamuts can look similar in a 2-D plot yet differ badly in the shadows or highlights.
An ICC profile is, in large part, a measured description of exactly this region plus the mapping into and out of it. That is why colour management works at all: with both gamuts described, software can compute which of your colours the destination cannot reproduce, and remap them predictably instead of letting the device clip them arbitrarily.
How the common gamuts relate
The overlap trap
The intuition "CMYK is just smaller" is only mostly true, and the exception matters. A coated-stock press produces dense, inky cyans and certain deep greens that sit OUTSIDE sRGB — so a workflow that squeezes everything through sRGB before converting to CMYK throws away printable colour. This is the practical argument for wide-gamut working spaces in print-destined photography, and for converting to CMYK from the richest source you have rather than from a web-ready derivative.
Out-of-gamut in practice
- A colour outside the destination gamut has no exact reproduction there — something must give, by definition, not by software failure.
- Relative colorimetric clips it to the nearest boundary colour; perceptual compresses the whole image so relationships survive. The rendering-intents article covers the trade-offs.
- Soft proofing shows the remapped result before you commit; gamut differences are precisely what it exists to reveal.
- The professional response to an out-of-gamut brand colour is a spot ink, not a stronger conversion setting.
How gamut size is (and is not) compared
Marketing often quotes "percentage of a gamut" figures — 98% sRGB, 90% P3. These are volume ratios and hide WHERE the missing region sits: a display missing 5% of sRGB in the near-neutrals is worse for retouching than one missing 10% in extreme saturated corners you rarely use. When gamut matters to your work, look at which regions differ, not one percentage.
Try it in PhotoAIA
- Open a saturated image and enable the soft proof against a CMYK profile.
- Toggle the proof and note which regions move — those are outside the press gamut.
- Switch the proof profile to an uncoated condition and watch the affected area grow.
- Compare the same regions under Perceptual vs Relative Colorimetric proof intents.
Questions
- Is a bigger gamut always better?
- For capture and working spaces, generally yes — you can always compress later. For DELIVERY, no: a wide-gamut file shown by a colour-unaware viewer oversaturates. Match the delivery space to the destination.
- Can two devices with the same gamut still disagree?
- Yes — gamut is the boundary, not the behaviour inside it. Tone response and grey balance differ between devices with near-identical gamuts, which is why profiles describe far more than the boundary.
- Where do I see out-of-gamut colours in PhotoAIA?
- Enable the soft proof against your destination profile — regions that change visibly are the ones being remapped. The proof runs the real LittleCMS conversion, not an approximation.