CRS Colour Toolbox for MATLAB

The CRS Colour Toolbox for MATLAB provides a set of functions and graphical tools for colour vision science. The toolbox was developed in collaboration with Dr Caterina Ripamonti and contains the essential tools to simplify measuring, calculating, manipulating and displaying calibrated colour visual stimuli.

Toolbox Features

• Spectroradiometric measurement of computer-controlled displays using SpectroCAL
• New display device characterisation procedures for ViSaGe and Psychtoolbox for Windows
• Colorimetric and physiologically based colour space visualisation, translation and manipulation routines
• Suite of example stimuli and complete experiments for ViSaGe and Psychtoolbox for Windows
• Full source code and documentation

Toolbox Schematic

SpectroCAL Measurement Control Panel

The Colour Toolbox uses the CRS SpectroCAL to accurately measure the spectral characteristics of a computer display and subsequently enable the specification visual stimuli in colorimetric and physiologically based colour spaces.

• Simple to use graphical Measurement Control Panel
• Measures spectral radiance, total radiance, photopic and scotopic luminance, chromaticity, colour temperature
• 2D plot of spectral radiance, other values tabulated
• Spectral radiance for each RGB output exported to MATLAB workspace

Display Device Calibration, Transfer Function Measurement and Characterisation

A new set of measurement and curve-fitting functions are provided that implement a robust and accurate gamma correction procedure. Unlike previous photometric and colorimetric solutions, the SpectroCAL measures spectral characteristics of the display over its full range. This means inaccurate measurements due to poorly implemented photopic filters are avoided. The toolbox implements also a new set of cone sensitivity based colour spaces especially designed for vision science.

• Simple to use graphical Measurement & Characterisation Control Panel
• Automated measurement of transfer function characterisation across full-scale range
• Provides a set of robust curve-fitting techniques to model a range of display device technologies including CRT and LCD displays
• Transfer function accounts for ‘Dark Light’
• Creates Gamma Correction tables for ViSaGe and Bits++

Colour Space Calculation, Manipulation and Translation Routines

A complete range of colorimetric and physiologically based colour spaces can be calculated and visualised using the Colour Space Explorer and the spectral radiance measurements provided by SpectroCAL. Pick and display any point in the calculated gamut for the selected colour space using the ViSaGe or Bits++ system (with Psychtoolbox for Windows), and easily convert values between colour spaces.

• Graphical visualisation tool
• 2D plots of display device Spectral Power Distribution
• 2D and 3D plots of colour spaces
• Choice of conventional colorimetric colour spaces including CIE 1931 2°, CIE 1964 10°, CIE 1976, CIELUV, CIELAB
• Display theoretical maximum and measured gamut
• Choice of physiologically based colour spaces with different cone fundamentals
• Includes support for Stockman & Sharpe, Smith & Pokorny
• Display theoretical maximum and measured gamut based on a selected white point (SML, MacLeod-Boynton, DKL)
• Pick and display a patch of colour from the selected colour space using ViSaGe or Psychtoolbox for Windows

Toolbox of MATLAB Routines for Colour Vision Research

An entire suite of colour space calculation, manipulation, visualisation and transformation routines are supplied as MATLAB M files. Full source code and documentation is provided allowing you to verify the veracity of our algorithms.
Additional routines are supplied for use with the ViSaGe system to make it simple to define and display stimuli in colorimetric (perceptual) and retinal (physiological) measurements. Functions are also provided to calculate:

• Scotopic Trolands
• Photopic Trolands
• Effects of macula pigment and lens yellowing (aging)
• Chromophore Bleached fraction

Proposed Example Stimuli and Experiments for ViSaGe

• Heterochromatic flicker photometry for MPOD
• Mondrian pattern for colour constancy
• Isoluminant chromatic Gabor stimuli (i.e. ColorFest) to measure CSF
• Ishihara style plates with luminance noise to test colour vision deficiencies
• Cone-isolating pattern-reversal grating stimulus for electrophysiology

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