# pngio

> **Tool `tools/formats/pngio.py`** (program, Formats). Read and write PNG pictures with the standard library alone.

Run it with `./gameframe run pngio ARGS` or `python3 tools/formats/pngio.py`. [Source on GitHub](https://github.com/tanepiper/game-frame/blob/main/tools/formats/pngio.py).

## Its own help

This is the help text in the tool itself, as `./gameframe tool pngio` prints it.

```text
Read and write PNG pictures with the standard library alone.

    from pngio import read_png, write_png, grey
    w, h, rgb = read_png('shot.png')        # rgb: bytes, 3 per pixel, rows top to bottom
    write_png('out.png', w, h, rgb)
    g = grey(w, h, rgb)                     # one byte per pixel

Usage: pngio.py FILE                        print the size, colour type and bit depth

It reads 8-bit greyscale, grey with alpha, RGB, RGBA and palette pictures (bit depth 8, or 1, 2
and 4 for palette and grey), with every filter. Alpha is dropped. It writes 8-bit RGB.

What it does not read: interlaced (Adam7) or 16-bit pictures. Convert those first, for example
with `sips -s format png` on macOS or ImageMagick's `convert -depth 8 -interlace none`.
```