How to Import FLI and FLC Files in GIMP

GIMP natively supports Autodesk Animator FLI and FLC animation formats, allowing users to open, inspect, edit, and convert these retro animation files directly without third-party plugins. When imported, GIMP processes the file using its internal animation decoder, breaking down the sequence so that each animation frame becomes an independent layer. This article details the import mechanism, layer structuring, color palette handling, and playback options available for FLI and FLC files within GIMP.

Native Plugin Support and Opening Files

GIMP includes a built-in file plugin specifically designed to read Autodesk Animator files. To import a file, navigate to File > Open, locate the .fli or .flc file, and select it. GIMP automatically recognizes the header, unpacks the run-length encoded (RLE) delta compression used by the format, and loads the entire sequence into the workspace.

Layer Structure and Frame Timing

Upon import, GIMP maps every frame of the animation to a discrete layer:

  • Layer Order: The first frame is placed at the bottom of the layer stack, while subsequent frames are stacked sequentially upward.
  • Frame Metadata: GIMP appends frame information, including frame numbers and timing metadata (in milliseconds), directly into the layer names (for example, Frame 1 (100ms)).
  • Frame Disposal: The decoder translates the animation's frame changes into standard full-frame layers, ensuring that delta-compressed changes are pre-rendered per frame for easy editing.

Color Mode Handling

Autodesk Animator formats are strictly 8-bit indexed color animations, supporting a maximum of 256 colors per frame with the potential for palette shifts between frames. When opening these files:

  • GIMP typically opens the file in Indexed color mode to preserve the original palette structure.
  • If you need to use filters, blending modes, or tools restricted under indexed mode, you must manually change the color space by going to Image > Mode > RGB.
  • Preserving the indexed palette is essential if you intend to export the file back to the original FLC format, as modern true-color palettes are incompatible with legacy Autodesk specifications.

Previewing and Editing

Once loaded, the animation can be reviewed using GIMP's built-in animation player:

  1. Navigate to Filters > Animation > Playback.
  2. Use the playback controls to step through frames, adjust the playback speed, and verify the animation sequence.

Individual frames can be modified using standard painting and transformation tools by selecting the corresponding layer.

Exporting and Conversion

After editing, GIMP allows you to re-export the project. While you can save the file back as an FLC animation using File > Export As, you can also convert legacy Autodesk animations into modern web formats such as animated GIF, WebP, or APNG by choosing the appropriate file extension during export.