Argyll File Formats
Author: Graeme Gill

# File formats that Argyll uses

Argyll uses a number of file formats for its operation, some that are external standards, and some that are unique to Argyll.
.ti1
.ti2
.ti3
.cal
.cht
.gam
.sp
CGATS
ICC
MPP
TIFF
VRML

## .ti1

Target Information 1 data. This is an ASCII text, CGATS, Argyll specific format, used to hold device value ready for creating a profiling test chart, as well as the estimated CIE color values for each value, used in laying out the test chart and reading validation purposes. Additional information on possible spacer and marking values that may be needed in creating a rendered test chart is also included. This file is typically created using the targen utility.

## .ti2

Target Information 2 data. This is an ASCII text, CGATS, Argyll specific format, used to hold device value that have been laid out in a test chart, together with each test patches location, and estimated CIE color values for each value used for reading validation purposes. This file is typically created using the printtarg or filmtarg utilities.

## .ti3

Target Information 3 data. This is an ASCII text, CGATS, Argyll specific format, used to hold device value and CIE/Spectral value pairs, the raw information needed to create device profiles. This file is typically created using the chartread, dispread, filmread, scanin, fakeread or one of the conversion utilities such as cb2cgats, kodak2cgats, logo2cgats. See TI3 file format for more detail.

## .cal

Device calibration information. This is ASCII text, CGATS, Argyll specific format, used to hold a description of device setup information that brings it to a desired calibration state. Created by dispcal, printcal, synthcal. See CAL file format for more detail.

## .cht

Test chart recognition file. This is ASCII text, CGATS, Argyll specific format, used to hold a description of a test chart, so that a raster image of the chart can be turned into device test values by the scanin utility. .cht files are created manually (usually in combination with scanin creating a boilerplate file containing the recognition parameters, but not the patch location information), or by the printtarg utility, when creating a test print chart that will be acquired in, rather than read by an instrument. See CHT file format for more detail.

## .gam

Gamut surface description. This is an ASCII text, CGATS, Argyll specific format, used to hold a 3 Dimensional surface description of a color gamut. Typical this is created using the iccgamut, tiffgamut, or mpplu utilities. The resulting file is typically viewed using the viewgam utility to convert one or more gamuts into a VRML file, or as input to collink, to describe a source colorspace gamut.

## .sp

Spectral illuminant description. This is an ASCII text, CGATS, Argyll specific format, used to hold a spectral description of an illuminant. Typically it is used to record a custom illuminant, for use in computing Fluorescent Whitening Agent compensation for reflective samples, as well as computing CIE tristimulus values from spectral samples.

### CGATS

CGATS.5 Data Exchange Format, from the Annex J, of the ANSI CGATS.5-1993 standard.
This is a general purpose ASCII file format suitable for representing color data, and widely used to store color test values. Argyll uses this as a base, human readable format, for a variety of purposes.

### ICC

ICC files are files that conform to the International Color Consortium, File Format for Color profiles. The ICC Profile Format attempts to provide a cross platform device profile format, that can be used to translate color data created on one device into another device's native color space. For a fuller explanation of what the ICC Profile Format is all about, please refer to http://www.color.org, and the profile specification. Argyll currently supports profiles that meet the V3.4 specification. These files are commonly named with a .icm extension on the Windows platform, .pr or .icc on the Macintosh and other platforms. As well as device profiles, the ICC format can also store device link profiles, abstract profiles and named color profiles. This file is typically created using the colprof or collink utilities. A device link profile is also a way of specifying a custom ink separation from (say) CMYK to the 6 or more colorants used by inkjet printers.

### MPP

Model based device profile format. This is an ASCII text, CGATS, Argyll specific format, used to hold the parameters to a general model based device profile. This is a less precise and general format than and ICC profile, but is a compact way of representing a devices response when it has a large number of color channels, or when very few measured data points are available for its construction. This file is typically created using the mpprof utility.

### TIFF

Tag Image File Format (TIFF), a widely used format within the graphic arts industries for storing image data. It handles various forms of compression, and various colorspaces, including RGB, CMYK and multi-channel files. See http://www.remotesensing.org/libtiff/. Argyll makes use of this as a default raster format.

### VRML

Virtual Reality Modeling Language file. This is a portable way of encoding 3 Dimensional objects (such as gamut surfaces). Typically these can be viewed with a suitable standalone VRML viewer, or a plug in for a web browser. VRML97 is International Standard ISO/IEC 14772-1:1997. See http://www.vrml.org/ for more information.