The functionality of ART is explained in detail in the ART Handbook. Here, we just give a brief overview of the seven executables plus the resource directory which are installed when ART is built.
- The main renderer:
This application takes scene files in
.armformat as input, and yields displayable images as output. It performs all the steps of image synthesis: reading a scene, preparing it for rendering, path tracing (which yields a spectral HDR image in
.artrawformat), and tone mapping. In normal operation,
artistdoes not delete the generated
.artrawfile, so that the resulting image can be further analysed and tone mapped.
- The tone mapper:
Mainly does what it says on the tin: it takes
.artrawimages as input, and turns them into either
.tifffiles for display. But in addition to classical tone mapping,
tonemapcan also extract spectral slices from
.artrawimages, and even “explode” a polarised
.artrawinto its spectral Stokes components (which yields a lot of
The polarisation visualisation tool:
.artrawimages which contain polarisation information, this app offers a variety of visualisation functions which are described in one of our publications.
The difference image generator:
For two colour input images, this app generates a false colour difference image according to the CIEDE2000 metric. Separate diff images for luminance, chroma and hue can also be generated. For spectral
.artrawinput images, it can also generate a plus/minus difference image for a given wavelength. The difference image can also be stored in the ART-specific lossless floating point single channel
.artgscformat, for further processing via
The image file manipulation tool:
Utility for the proprietary image formats of ART,
.artcsp(colour space). Functions offered are computation of SNR and diff values of two images, addition of two images, plus re-scaling of single images and querying of individual pixel values.
A tool to convert floating point single channel
.artgscimages into displayable false colour or greyscale images. It offers a few options more than
bugblatterfor the formatting of
.artgscoutput, and mainly exists as a separate app because
.artgscimages were, at various points during development, used as debug output for certain subsystems.
The scene file translator:
This tool translates the human-readable
.armscene file format of ART to the parseable internal
artistautomatically translates any
.armfile it is fed, but this tool allows one to perform translations without having to invoke the actual renderer.
In addition to these seven executables, a resource directory called
ART_Resource is installed. Where it is installed depends on your system type: on MacOS, it is usually placed in
~/Library, under Linux in
~/lib (if you chose to install ART in your home directory, that is). The directory contains:
- Spectral reference data, including Macbeth Color Checker and Munsell Book of Color reflectance data
- Luminaire data for CIE reference lamps
- Properties of a number of materials, such as certain metals, and glass types
- ICC profiles for various RGB spaces
- But also internal machinery needed for the
arm2artfile translation machinery.