This is a triangle color picker made with the Aseprite scripting API. It is intended for use with Aseprite version 1.3 or newer.
To download this script, click on the green Code button above, then select Download Zip. You can also click on the aseTriPicker.lua file. Beware that some browsers will append a .txt file format extension to script files on download. Aseprite will not recognize the script until this is removed and the original .lua extension 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. Move the Lua script into the folder that opens. 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 aseTriPicker.lua to launch the dialog.
If an error message in Aseprite's console appears, check if the script folder is on a file path that includes characters beyond UTF-8, such as 'é' (e acute) or 'ö' (o umlaut).
A hot key can be assigned to the script by going to Edit > Keyboard Shortcuts. The search input box in the top left of the shortcuts dialog can be used to locate the script by its file name. The dialog can be closed with Alt+X. The foreground color can be retrieved with Alt+F; the background color, with Alt+B.
When the canvas has focus, left click will change the foreground color and right click will adjust the background color. Clicking on the swatches in the bottom-left corner will swap the fore and background color.
When the picker is wider than it is high, it will show text information about the color. Hue is expressed in degrees; other color data is expressed in percentages.
In HSV, when a color's saturation is zero, its hue is undefined. When it's value is zero, both its hue and its saturation are undefined. This is easier to understand by visualizing the HSV model as an upside-down cone. Ultimately, the HSV method for representing color is deeply flawed. Neither this color picker, nor HSV in general, should be used to create harmonious colors or determine shades of a hue.
I would encourage readers to research alternatives like CIE LAB, SRLAB2, OK LAB, HSLuv or Okhsl. An SR LAB 2 picker is available at AsepriteAddons; Okhsl pickers can be found here and here.
To modify these scripts, see Aseprite's API Reference. There is also a type definition for use with VS Code and the Lua Language Server extension.
This script was tested in Aseprite version 1.3.2 on Windows 10. Its user interface elements were tested with 100% screen scaling and 200% UI scaling. Please report issues in the issues section on Github.
