Colour management
The CMYKProfile, RGBProfile and rendering-intent attributes on the IDML Document element, what the profile names mean, and why rendering needs the profile.
A document names the colour profiles its numbers are meant for; it does not contain them. The same CMYK values look different under a different profile.
In short The <Document> element in designmap.xml carries the document's working
spaces: CMYKProfile and RGBProfile, each the name of an ICC profile, plus the rendering
intents SolidColorIntent, AfterBlendingIntent and DefaultImageIntent, and the
CMYKPolicy and RGBPolicy for files that arrive with other profiles. Only the names travel
with the file. To show CMYK colours accurately, a reader needs the profile itself, found by
that name.
The attributes on <Document>
| Attribute · Document | Values | Paged | paged.set |
|---|---|---|---|
| CMYKProfile | builtin / text | read | |
| RGBProfile | builtin / text | read | |
| SolidColorIntent | UseColorSettings | read | |
| AfterBlendingIntent | UseColorSettings | read | |
| DefaultImageIntent | UseColorSettings | read | |
| CMYKPolicy | ColorPolicyOff | CombinationOfPreserveAndSafeCmyk | not read | |
| RGBPolicy | ColorPolicyOff | PreserveEmbeddedProfiles | not read |
The profile names
CMYKProfile and RGBProfile hold a profile's description, the name InDesign shows in its
colour settings. Across the documents surveyed for this reference:
| Attribute | Value | Documents | What it describes |
|---|---|---|---|
CMYKProfile | Coated FOGRA39 (ISO 12647-2:2004) | most | Offset printing on coated paper, the common European standard |
CMYKProfile | U.S. Web Coated (SWOP) v2 | many | Web offset printing on coated paper, a common North American standard |
CMYKProfile | Coated FOGRA27 (ISO 12647-2:2004) | a few | An older coated-paper offset condition |
RGBProfile | sRGB IEC61966-2.1 | almost all | The standard screen RGB space |
RGBProfile | Adobe RGB (1998) | a few | A wider RGB space used in photography |
| either | $ID/ | a few | No profile named |
The CMYK profile is the one that matters most. A CMYK ColorValue is ink coverage, and what
that coverage looks like depends on the press and paper the profile describes: 65 45 30 10
is a different blue-grey on coated and on uncoated stock. RGB colours depend on the RGB
profile in the same way, although sRGB is so common that a reader assuming it is rarely far
off. Lab colours need no profile; they describe a colour directly.
Rendering intents
When a colour has to move from one profile's space into another's, from the CMYK working space to the screen for example, a rendering intent decides how colours that do not fit are handled. The document carries three:
SolidColorIntentfor flat colours: swatches, fills, strokes, text;DefaultImageIntentfor placed images (an<Image>can override it with its ownImageRenderingIntent);AfterBlendingIntentfor colours that result from transparency.
Every surveyed document has UseColorSettings for all three, which defers to the colour
settings of the application that opens the file.
Profile policies
CMYKPolicy and RGBPolicy record what InDesign does with content that carries a different
profile. In the surveyed files CMYKPolicy is CombinationOfPreserveAndSafeCmyk or
ColorPolicyOff, and RGBPolicy is PreserveEmbeddedProfiles or ColorPolicyOff. They
govern placing and pasting in InDesign, not how the file's own swatches look.
Rendering depends on the profile being available
An IDML file contains no ICC profiles. A reader that wants the colours InDesign shows has to find the named profile on its own system or be given it, and convert CMYK and RGB through it. A reader without the profile can only approximate; a simple formula from CMYK to RGB is recognisably off for saturated colours. Two readers that disagree on colour usually disagree on the profile, not on the numbers.
In Paged: no profile ships with the engine.
paged-inspecton the command line looks for the document's named profile among the Adobe colour profiles installed on the machine. In the browser the engine converts colour with qcms (natively with lcms2) and gets full colour management once the host registers the profile's bytes under the document's profile name and applies its colour settings; until then CMYK is converted by a simple formula. Lab colours are converted without a profile. Supported · verified
Frequently asked questions
Does an IDML file embed its colour profiles?
No. CMYKProfile and RGBProfile on <Document> are names. The profiles themselves have to
be available to whoever renders the file.
What does Coated FOGRA39 (ISO 12647-2:2004) mean?
It is the description of the ICC profile for offset printing on coated paper under
ISO 12647-2, the most common CMYK working space in the surveyed documents.
Why do CMYK colours look different in different viewers? Usually because one of them converts through the named profile and the other does not have it, or uses another profile.
What does UseColorSettings mean for an intent?
That the document has no intent of its own and defers to the opening application's colour
settings. It is the value in every surveyed file.
Do Lab colours need a profile? No. Lab describes a colour independently of any device, so it converts to the screen without one.
Spot & process color
Process and spot colours in IDML, how a spot ink is previewed through its alternate, mixed inks, overprint and colour groups.
Images & graphics
In IDML a picture is always placed inside a frame; the frame crops it, the graphic element places it, and a link names the file that holds the pixels.