QOI — The “Quite OK Image Format” for fast, lossless image compression

Implementation of the QOI format using Go, along with a simple tool to visualise and analyze QOI's compression.

See QOI for an overview of what QOI is. The "quick rundown" is that QOI is an image format which:

1. Has a remarkably simple specification (it fits onto a single page).
2. Compresses images at high speed, locally and in a single pass.
3. Achieves a compression ratio close to that of PNG.

Visualisation:

Since QOI compresses every pixel (or run of pixels, visualised with cyan) as an individual chunk, we are able to visualise QOI's compression by coloring the individual pixels according to which type of chunk was used. This library includes a function to automatise this process, and which also provides some basic statistical data on the results:

qoi_OP_RGB: Used to encode 6742 pixels (4.101%), using 20226 bytes (9.591%) total. Color: {255 0 0 255}

qoi_OP_RGBA: Used to encode 0 pixels (0.000%), using 0 bytes (0.000%) total. Color: {255 0 255 255}

qoi_OP_INDEX: Used to encode 38524 pixels (23.433%), using 38524 bytes (18.269%) total. Color: {0 255 0 255}

qoi_OP_DIFF: Used to encode 31311 pixels (19.046%), using 31311 bytes (14.848%) total. Color: {255 255 0 255}

qoi_OP_LUMA: Used to encode 52532 pixels (31.954%), using 105064 bytes (49.823%) total. Color: {0 0 255 255}

qoi_OP_RUN: Used to encode 35291 pixels (21.467%), using 15750 bytes (7.469%) total. Color: {0 255 255 255}

Overall compression ratio: 32.067368%