Library implementing parsing of image formats such as PNG, BMP, PPM

The imagelib library implements image formats such as PNG, BMP, and PPM in OCaml, relying on only one external dependency: 'decompress'.

Unix-dependent functionality such as reading or writing to files in the filesystem are packaged separately in the 'imagelib-unix' OPAM package.

Supported image formats:

• PNG (full implementation of RFC 2083),
• PPM, PGM, PBM, ... (fully supported),
• BMP (read-only)
• JPG (only image size natively, conversion to PNG otherwise),
• GIF (only image size natively, conversion to PNG otherwise),
• XCF (only image size natively, conversion to PNG otherwise),
• Utility functions for handling unimplemented formats are available in the 'imagelib-unix' OPAM package. See that package description for more info.

As imagelib only requires 'decompress', it can be used together with js_of_ocaml to compile projects to Javascript, or from MirageOS unikernels.