add PNG compression

[JoKalliauer]

Add png-optimization

Input=Output (573KB)

LargePngEmbeddedSCs.svg.txt

Expected Output (196KB)

small.svg.txt

[Ede123]

Might be a nice addition in principle, but

• SVGs containing raster graphics are basically flawed to start with
• Not really scours primary goal (it's an SVG optimizer not a PNG optimizer)
• Only covers one possible raster format
• Will require additional dependencies.
• Most likely can't be solved in Python (if people know Python modules to do PNG optimization feel free to add them here)

Personally I'd go for something similar to zopflipng with which I've made good experiences in the past, but obviously that would need us to call out to an executable.

[JoKalliauer]

I assume it is out of scope, I did not expect that it will considered for implementing (optimiziation needs prozessing-time and as said it is a SVG optimizer not a PNG optimizer)

In lager images often Rasterimages take most of the space. For such svg classical svg optimization is useless, but png optimization is essential, therefore large file-reduction, no svg-breaking and only needs prozessing-time if image are embedded.

SVGs render require rendering PNGs and JPEGs, see https://github.com/RazrFalcon/resvg/issues/214#issuecomment-589828455 maybe also https://www.w3.org/Graphics/SVG/About.html

lossless JPEGcompression is imho minimal, lossy compression might be undesired.

PNGoptimization Benchmark: https://css-ig.net/png-tools-overview GitHub: https://github.com/topics/png-compression Python: https://cloudinary.com/blog/image_optimization_in_python

Python modules to do PNG optimization feel free to add them here

I do not know any, but maybe one of the following would fit?

• Python itself https://cloudinary.com/blog/image_optimization_in_python
• TinyPNG https://tinypng.com/developers/reference/python
• tinify https://pypi.org/project/tinify/
• CRUNCH https://pythonawesome.com/a-tool-for-lossy-png-image-file-optimization/
• pngquant https://pypi.org/project/pngquant/
• optimize-images https://pypi.org/project/optimize-images/
• Pillow https://pillow.readthedocs.io/en/4.1.x/
• img4web https://github.com/joedicastro/img4web
• smush https://github.com/thebeansgroup/smush.py
• scikit https://scikit-image.org/
• reindexing https://github.com/Helias/PNG-reindexing
• zopflipng https://github.com/hhoy/python-zopflipng