Converting PNG32 to PNG8 with PIL while preserving transparency

Question

I would like to convert a PNG32 image (with transparency) to PNG8 with Python Image Library. So far I have succeeded converting to PNG8 with a solid background.

Belo

Answer 1

This is an old question so perhaps older answers are tuned to older version of PIL?

But for anyone coming to this with Pillow>=6.0.0 then the following answer is many magnitudes faster and simpler.

im = Image.open('png32_or_png64_with_alpha.png')
im = im.quantize()
im.save('png8_with_alpha_channel_preserved.png')