Colour Simulations, A Desktop Application for Windows


User Guide

ColourSimulations version 1.1.4

Introduction

The Colour Simulations application applies a colour transform to the underlying screen. Open the media of interest with the default windows application then simply place the ColourSimulations application window above the media to see the colour transformation. The colour transform is applied in real-time so the application can be used with video and also with games played in windowed mode.

Colour normal viewers should select 'Simulation' by pressing 'S' or selecting Simulation from the application menu. The window title will start with 'Simulation -'.

For users with colour vision deficiency a number of options are available to assist with colour discrimination, including the Daltonize algorithm, colour swaps and filters.

The application menu can be accessed by right-clicking anywhere on the window and the main window moved and resized by dragging with the left mouse button.

Colour Deficiency Type

The inherited forms of red-green colour-blindness can be simulated:

Press 'P' for Protanomalous/Protanope or select 'Protan' from the application menu.

Press 'D' for Deteranomalous/Deutanope or select 'Deutan' from the application menu.

Severity

Severity can be adjusted by scrolling the mouse-wheel or by pressing the + and - keys.

The range of severity goes from 0% (normal vision) to 100% (dichromat).

For Protanomalous vision the severity range is of the order 75% to 95% (*).

For Deuteranomalous vision the severity range is of the order 55% to 95% (*).

(* Approximate ranges based on known variations of photopigment molecules)

Simulation

The simulation option simulates colour vision deficiency for colour normal viewers.

Press 'S' or select Simulation from the application menu. The window title will start with 'Simulation -'.

The simulation algorithm reduces the colour space to the blue-yellow axis while preserving the black-white achromatic scale. Confusion lines are consistent with the chromaticity xy confusion points of [0.753,0.247] for Protan deficiency and [1.00,0.00] for Deutan deficiency.

Daltonize

The Daltonize algorithm (www.daltonize.org) assists viewers with colour vision deficiency.

Press 'A' or select Daltonize from the application menu.

The algorithm applies contrast in proportion to the missing colour components: Red will get lighter and the other colours darker. The missing colour components are estimated by the simulation algorithm, here the mouse-wheel can be used to control the level of correction: note there is no right or wrong correction, the user can adjust the level of correction to suite the image, selecting an appropriate level of correction according to the detail revealed in the image.

Inverse Transform

The inverse transform is of interest to anomalous viewers (as opposed to dichromats) as it give an indication of normal colour perception for colour deficient viewers. Note the range of colours that can be successfully transformed is very small, depending on the severity of the observer. Users should start with 0% severity and move up. Colours will quickly become saturated as the transformed colours go outside of the colour space that can be displayed.

Colour Swaps and Filters

Swapping red and blue is another tool for the colour deficient viewer to discriminate confused colours. This option does have the issue of introducing other colour confusions so its usefulness is very dependant on the image.

Swaping red and blue is selected from the application menu and the ammount of colour swapped controlled with the mouse wheel from 0% to 100%.

Other colour swaps can be selected from the application menu: Other colour effects->Colour Swap

Colour filters may also be useful, from the application menu: Other colour effects->Colour Filter

RGB Cube

The RGB cube is a visual display of the colour space.

Press 'R' to display the cube or from the application menu select: Colour space Window-> RGB Cube

The cube can be rotated with the left mouse-button

As the severity of the colour vision deficiency is increased the cube is tranformed to show the available colour space of the colour deficient viewer. Note the outline of the colour-normal cube is always displayed for reference.

Chromaticity Diagram

The CIE xy Chromaticity diagram is another visual display of the colour space.

Press 'C' to display the diagram or from the application menu select: Colour space Window-> Chromaticity diagram

The curve of spectral colours is shown together with the RGB colour space displayed by a typical computer monitor.

The RGB colour-normal triangle outline is always shown for reference while the colour gamut reduces with severity.

Photoreceptor response curves

The Photoreceptor response curves show the wavelength absorption of the S, M and L cone cells in the retina.

Press 'E' to display the curves or from the application menu select: Colour space Window-> Photoreceptor response curves

As the severity is increased the reduced separation of the M and L cone response can be visualized.

Other Colour Effects

These colour transforms are provided as utilities, select from the appliction menu:

Invert

Greyscale

Brightness

Contrast

Saturation

Circadian light block (removes blue and reduces green colour output)

Hit Transparent Mode

This option allows the user to work on an underlying document or application.

Press H or from the application menu select: View Options-> Hit Transparent

A control window opens giving the user access to the application menu (right-click) and the option to exit hit-transparent mode.

Full screen mode

Like the hit-transparent option a control window appears giving the user access to the application menu and the option to exit full-screen mode.

Screen Capture

Press Ctrl-C to copy an image to the system clipboard.

The captured image gives the tranformed image displayed in the application window.

For fine positioning of the window use the arrow keys for pixel position adjustment and shift-arrow keys for height/width adjustment.

Note this option is not working for dual monitor setups.