How do I optimize an image (Loseless compression) to reduce the file size of an image?

[trymeouteh]

Question about an existing feature

What are you trying to achieve?

What is the bet way to optimize (compressing an image using loseless compression) to reduce the file size of an image. I would like to know how to do this for JPEG images, PNG images, GIF images and WEBP images.

When you searched for similar issues, what did you find that might be related?

By going through the documentation and stackoverflow anwsers.

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

This is what I came up with so far and does work well for JPEG, PNG and WEBP images. However I cannot seem to get much optimization on GIF images (perhaps my GIF image is already optimized to its fullest)

import sharp from 'sharp';

await sharp('input.jpg').jpeg({ mozjpeg: true }).toFile('output.jpg');
await sharp('input.png').png({ compressionLevel: 9, quality: 100 }).toFile('output.png');
await sharp('input.gif').toFile('output.gif');
await sharp('input.webp').webp({ loseless: true, quality: 80 }).toFile('output.webp');

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

Download link for each image example...
https://ufile.io/f/67ij3

[lovell]

If you need to use lossless compression then JPEG, GIF and palette-based PNG are off-limits as they are lossy. That leaves you with full colour PNG and lossless (rather than "loseless") WebP. Remove the quality settings from your examples and that's probably the best you can do.

[trymeouteh]

Remove the quality settings from your examples and that's probably the best you can do.

Are the quality settings used for the PNG and WEBP images above going to be noticeable to the naked eye?

[lovell]

You'll need to experiment with your own images to determine subjective measures like this. Perhaps try tooling such as https://github.com/cloudinary/ssimulacra2 to help.