This repository is an adaptation of libDaltonLens by Nicolas Burrus to Lua. The code simulates how individuals with color vision deficiency (CVD), also known as color blindness, view an image. As with the original repository, this code uses the Unlicense, and is released to the public domain.

The code has been modified for use with the Aseprite scripting API.

To get this script, click on the green Code button above, then select Download Zip. You can also click on the aseDaltonLens.lua file. Beware that some browsers will append a .txt file format to script files on download; Aseprite will not recognize the script until this is removed and the original .lua format is used. There can also be issues with copying and pasting. Be sure to click on the Raw file button; do not copy the formatted code.

To use this script, open Aseprite. In the menu bar, go to File > Scripts > Open Scripts Folder. Copy and paste the Lua script from this repository into that folder. Return to Aseprite; go to File > Scripts > Rescan Scripts Folder (the default hotkey is F5). The script should now be listed under File > Scripts. Select aseDaltonLens.lua to launch the dialog.

To assign a hotkey to the dialog script go to Edit > Keyboard Shortcuts. Once the dialog is open, Alt+O is the keyboard shortcut for the OK button. Alt+C is the shortcut for the CANCEL button.

Upon activation, the script will duplicate the active sprite, convert it to RGB color mode, flatten its layers and then create a new layer with the CVD simulation of the source images.

This is an animated plot for the three types of CVD, protanopia, deuteranopia and tritanopia:

The plot was made with SRLAB2, a variant of CIE LAB. The plotted points are the sRGB primary and secondary colors: red (R), yellow (Y), green (G), cyan (C), blue (B) and magenta (M). Note that these 6 colors are not located at the same angle -- nor are they the same angular distance from one another -- as they would be if they were plotted on an HSV/HSL color wheel.

Common-place labels for the three types of CVD, such as "Red-Green" or "Blue-Yellow" weakness, have been avoided because they contribute to the misunderstanding of CVD.

For more information, Burrus's articles are recommended:

• Review of Open Source Color Blindness Simulations
• Understanding LMS-based Color Blindness Simulations
• Evaluating Color Blindness Simulations