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Documentation Index

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Aseprite can load and save GIMP Palettes (.gpl files) with an extension that supports alpha channel information.

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Format Specification

Aseprite extends the standard GIMP Palette format by adding alpha values to each color entry. Here’s an example: 
GIMP Palette
Channels: RGBA
#
  0   0   0   0 Transparent
254  91  89 255 Red
247 165  71 255 Orange
243 206  82 255 Yellow
106 205  91 255 Green
 87 185 242 255 Blue
209 134 223 255 Purple
165 165 167 255 Gray

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Requirements

To use alpha channel support in GIMP Palettes:
  1. You must specify Channels: RGBA in the header
  2. Each color entry must contain four values: Red, Green, Blue, and Alpha
  3. All color values range from 0 to 255
  4. Color names are optional (but can be included after the values)

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Format Details

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Header

GIMP Palette
Channels: RGBA
#
The header consists of:
  • GIMP Palette - Standard format identifier
  • Channels: RGBA - Specifies that this palette includes alpha channel data
  • # - Comment line (optional)

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Color Entries

Each color entry follows this format: 
RED GREEN BLUE ALPHA [Name]
Where:
  • RED, GREEN, BLUE, ALPHA are integer values from 0 to 255
  • Name is an optional color name
  • Values can be padded with spaces for alignment

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Example Entry

254  91  89 255 Red
This defines a red color with:
  • Red: 254
  • Green: 91
  • Blue: 89
  • Alpha: 255 (fully opaque)
  • Name: “Red”

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Compatibility Notes

This is an Aseprite-specific extension. GIMP does not support palettes with alpha values, so .gpl files with alpha channel information may not load correctly in GIMP.

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No Alternative Channels

There are no plans to provide different values for the Channels property. The format only supports RGBA channel configuration.

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Usage in Aseprite

Aseprite will automatically detect and handle the alpha channel when:
  • Loading a .gpl file with Channels: RGBA header
  • Saving a palette with transparency information to .gpl format
When saving a palette that includes transparent colors, Aseprite will automatically use this extended format.

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