I have a compressed PNG image
compressed.png. I can convert it to an uncompressed PNG
decompressed.png using GIMP (saving as PNG and setting compression level to 0). How can this be done on the command line (Linux)?
convert compressed.png -compress None decompressed.png
convert compressed.png +compress decompressed.png
convert compressed.png -quality 0 decompressed.png
convert compressed.png -quality 00 decompressed.png
just wrote an ordinary compressed PNG.
Aside: why would you want an uncompressed PNG?
- You want to support efficient (binary) diffs of the image data, while still using other features of the PNG format (as opposed to storing raw image data or BMP).
- You want to compress several PNGs together in a tarball or 7z archive, but want to keep using PNG features. If the images are sufficiently similar this can give a better compression ratio than compressing individually.
- Useful as a baseline size for testing PNG optimizers.