.ICC File Format – Tags

A2B0 AToB0Tag

The conversion from the device (or colour encoding, or the PCS in an abstract profile) to the PCS. In most classes it is the perceptual intent; in a DeviceLink it is the whole conversion from the first device to the last, for the intent the header names. Types: lut8Type, lut16Type or lutAToBType (version 2: the first two).

A2B1 AToB1Tag

Device to PCS, colorimetric: media-relative, and the base for ICC-absolute. Same types as A2B0.

A2B2 AToB2Tag

Device to PCS, saturation. Same types as A2B0.

B2A0 BToA0Tag

The PCS to the device or colour encoding, perceptual. Types: lut8Type, lut16Type or lutBToAType (version 2: the first two).

B2A1 BToA1Tag

PCS to device, colorimetric. Same types as B2A0.

B2A2 BToA2Tag

PCS to device, saturation. Same types as B2A0.

D2B0 DToB0Tag

Device to PCS with floating-point values throughout, perceptual; it overrides A2B0 for a CMM that supports every element in it. Type: multiProcessElementsType.

D2B1 DToB1Tag

Device to PCS, floating point, media-relative colorimetric; overrides A2B1.

D2B2 DToB2Tag

Device to PCS, floating point, saturation; overrides A2B2.

D2B3 DToB3Tag

Device to PCS, floating point, ICC-absolute colorimetric, stored directly: the media white point is not used to work it out.

B2D0 BToD0Tag

PCS to device, floating point, perceptual; overrides B2A0. Type: multiProcessElementsType.

B2D1 BToD1Tag

PCS to device, floating point, media-relative colorimetric; overrides B2A1.

B2D2 BToD2Tag

PCS to device, floating point, saturation; overrides B2A2.

B2D3 BToD3Tag

PCS to device, floating point, ICC-absolute colorimetric, stored directly.

gamt gamutTag

A table from PCS values to one output: 0 when the colour is inside the device’s gamut, anything else when it is outside (version 2 adds that a larger number is at least as far out). Types: lut8Type, lut16Type or lutBToAType.

pre0 preview0Tag

A preview: PCS to device and back to the PCS, combining B2A0 and A2B1, to show on screen how a print will look. Types: lut8Type, lut16Type, lutAToBType or lutBToAType.

pre1 preview1Tag

The preview through B2A1 and A2B1. Types: lut8Type, lut16Type or lutBToAType.

pre2 preview2Tag

The preview through B2A2 and A2B1. Types: lut8Type, lut16Type or lutBToAType.

rXYZ redMatrixColumnTag

The first column of the matrix of a three-component matrix-based profile: the PCSXYZ of the red channel at full strength, relative to the PCS white. Version 2 called it the redColorantTag. Type: XYZType.

gXYZ greenMatrixColumnTag

The second column, for green. Type: XYZType.

bXYZ blueMatrixColumnTag

The third column, for blue. Type: XYZType.

rTRC redTRCTag

The red tone reproduction curve: device value to linear value. Its first entry stands for no colorant (white) or no phosphor (black), its last for 100 %. Types: curveType or parametricCurveType (version 2: curveType).

gTRC greenTRCTag

The green tone reproduction curve. Types: curveType or parametricCurveType.

bTRC blueTRCTag

The blue tone reproduction curve. Types: curveType or parametricCurveType.

kTRC grayTRCTag

The grey tone reproduction curve of a monochrome profile: its first entry is black and its last white. Types: curveType or parametricCurveType.

wtpt mediaWhitePointTag

The nCIEXYZ of the media white, used to work out ICC-absolute colorimetry. Measurements made under another white are adapted to the PCS white with the chad matrix first. For a display, version 4 sets it to the PCS illuminant, D50; version 2 display profiles often hold the display’s own white instead. Type: XYZType.

bkpt mediaBlackPointTag

The media black point, referenced to the PCS; in version 2, when it is missing, (0, 0, 0) is assumed. Version 4 kept it up to 4.2 (ICC.1:2004), measured and adapted to D50 like the white point and not used for ICC-absolute colorimetry; ICC.1:2010 (4.3) and ICC.1:2022 no longer define it, and fix the perceptual reference medium’s black point instead. Type: XYZType.

lumi luminanceTag

The absolute luminance of an emissive device in Y, in candelas per square metre; X and Z are zero. Type: XYZType.

chad chromaticAdaptationTag

A 3 × 3 matrix, nine s15Fixed16Numbers row by row, that converts nCIEXYZ measured under the actual adopted white to nCIEXYZ under the PCS’s D50, with complete adaptation. It must be invertible; the Bradford transform is recommended. It was added in version 2.4 (ICC.1:2001-04). The explorer works out the white it adapts from by inverting it. Type: s15Fixed16ArrayType.

chrm chromaticityTag

The chromaticities of the phosphors or colorants, measured and not adapted. Type: chromaticityType.

meas measurementTag

An alternative measurement specification, such as D65 instead of D50: observer, backing, geometry, flare and illuminant. Type: measurementType.

view viewingConditionsTag

The viewing conditions: the illuminant and surround in absolute XYZ and the illuminant type. Type: viewingConditionsType.

ciis colorimetricIntentImageStateTag

What the colorimetric intents’ PCS values represent, when it is not picture-referred colorimetry. Type: signatureType, one of:

For the scene and focal plane states the media white point is the encoding’s maximum white and may have Y above 1.0, and the actual viewing conditions go in view.

rig0 perceptualRenderingIntentGamutTag

The reference medium gamut of the PCS side of A2B0 and B2A0. The only value defined is prmg, the perceptual reference medium gamut of ISO 12640-3. Type: signatureType.

rig2 saturationRenderingIntentGamutTag

The same for the saturation tags A2B2 and B2A2; again only prmg. Type: signatureType.

desc profileDescriptionTag

The profile’s name for showing to people, in one or more languages. It has no fixed link to the file name. Type: multiLocalizedUnicodeType; in version 2, textDescriptionType.

cprt copyrightTag

The copyright notice. Type: multiLocalizedUnicodeType; in version 2, textType.

dmnd deviceMfgDescTag

The device manufacturer’s name for display. Type: multiLocalizedUnicodeType (version 2: textDescriptionType).

dmdd deviceModelDescTag

The device model’s name for display. Same types.

vued viewingCondDescTag

The viewing conditions, described in words. Same types.

scrd screeningDescTag

The screening, described in words. Version 2 only. Type: textDescriptionType.

targ charTargetTag

The characterisation data the profile was made from. The first seven characters say what follows: ICCHDAT, a space and the reference name of a data set in the ICC’s Characterization Data Registry, ended by a zero byte; or the identifier of a data file format defined in an ANSI or ISO standard (such as a CGATS measurement file), with the whole file following. Type: textType.

calt calibrationDateTimeTag

When the device was calibrated. Type: dateTimeType.

tech technologyTag

The device’s technology. Type: signatureType, one of:

meta metadataTag

Metadata about the profile as name and value pairs, with names and values taken from the ICC’s metadata registry. Type: dictType. The tag and the type were adopted in 2010 for both version 2 and version 4 profiles, from the ICC proposal Dictionary Type and Metadata TAG Definition, and joined the ICC.1 text in ICC.1:2022 (versions).

clrt colorantTableTag

The colorants of the device side by name and PCS value, in channel order. Required for output and DeviceLink profiles whose data colour space is an xCLR space. In a DeviceLink only PCSLAB values are allowed. Type: colorantTableType.

clot colorantTableOutTag

The colorants of the output side of a DeviceLink, with PCSLAB values. Type: colorantTableType.

clro colorantOrderTag

The order the colorants are laid down in, when it differs from the channel order (an ink tower printing KCMY, for example). Type: colorantOrderType.

ncl2 namedColor2Tag

A list of named colours, each with a PCS value and optionally device values. Required in a NamedColor profile. Type: namedColor2Type.

ncol namedColorTag

The first form of named colours, replaced by ncl2. Version 2 only. Type: namedColorType.

resp outputResponseTag

The device’s reference response: measured colorant amounts against device codes, so that a drifting device can be corrected without a new profile. Type: responseCurveSet16Type.

pseq profileSequenceDescTag

The profiles that were combined into a DeviceLink, in order, from the source to the destination, with the final profile last: each one’s device manufacturer, model, attributes, technology and descriptions. Required in a DeviceLink. Type: profileSequenceDescType.

psid profileSequenceIdentifierTag

The Profile IDs and descriptions of the profiles combined. Type: profileSequenceIdentifierType.

cicp cicpTag

Coding-independent code points (ITU-T H.273) naming the video colour encoding the profile is equivalent to: primaries, transfer function, matrix and range. Allowed only in input and display profiles whose data colour space is RGB, YCbCr or XYZ. Added in version 4.4. Type: cicpType.

crdi crdInfoTag

The PostScript product name the profile is for, and the names of its companion colour rendering dictionaries (CRDs) for the four intents. Type: crdInfoType.

devs deviceSettingsTag

The device settings (resolution, media, halftone) the profile was made for, by platform. Type: deviceSettingsType.

ps2s ps2CSATag

A PostScript Level 2 colour space array. Type: dataType.

ps2i ps2RenderingIntentTag

The PostScript Level 2 rendering intent name. Type: dataType.

psd0 ps2CRD0Tag

A PostScript Level 2 colour rendering dictionary, perceptual. Type: dataType.

psd1 ps2CRD1Tag

The same, colorimetric. Type: dataType.

psd2 ps2CRD2Tag

The same, saturation. Type: dataType.

psd3 ps2CRD3Tag

The same, ICC-absolute colorimetric. Type: dataType.

scrn screeningTag

Halftone screening: frequency, angle and spot shape for each channel. Type: screeningType.

bfd ucrbgTag

Under-colour removal and black generation curves, and a description of how they were made. It is descriptive only and takes no part in the conversion. Type: ucrbgType.