GIF output palette size doubles (from 8 to 16)

Possible bug

Is this a possible bug in a feature of sharp, unrelated to installation?

• Running npm install sharp completes without error.
• Running node -e "require('sharp')" completes without error.

If you cannot confirm both of these, please open an installation issue instead.

Are you using the latest version of sharp?

• I am using the latest version of sharp as reported by npm view sharp dist-tags.latest.

If you cannot confirm this, please upgrade to the latest version and try again before opening an issue.

If you are using another package which depends on a version of sharp that is not the latest, please open an issue against that package instead.

What is the output of running npx envinfo --binaries --system --npmPackages=sharp --npmGlobalPackages=sharp?

System: OS: macOS 12.6 CPU: (8) x64 Apple M1 Pro Memory: 28.89 MB / 16.00 GB Shell: 3.2.57 - /bin/bash Binaries: Node: 14.17.2 - ~/.nvm/versions/node/v14.17.2/bin/node npm: 6.14.13 - ~/.nvm/versions/node/v14.17.2/bin/npm npmPackages: sharp: ^0.31.1 => 0.31.1

What are the steps to reproduce?

• Take any input animated gif
• Call await sharp('input_filename.gif', { animated: true }).toFile('output_filename.gif');
• File size is more than double the original.

What is the expected behaviour?

Output file size should be the same or nearly the same as the input file size.

Please provide a minimal, standalone code sample, without other dependencies, that demonstrates this problem

await sharp('input_filename.gif', { animated: true }).toFile('output_filename.gif');

Please provide sample image(s) that help explain this problem

https://media.giphy.com/media/jUwpNzg9IcyrK/giphy.gif

[lovell]

The new interFrameMaxError and interPaletteMaxError GIF options are exposed in commit https://github.com/lovell/sharp/commit/5740f4545efd2c4fd0d98a2b6104f8e0da111e66 and will be part of v0.31.3.

Example usage:

// interFrameMaxError API available from v0.31.3
await sharp('in.gif', { animated: true })
  .gif({ interFrameMaxError: 8 })
  .toFile('optim.gif');

[lovell]

v0.31.3 now available with support for interFrameMaxError and interPaletteMaxError.