更改.gif图像中每个像素的颜色数量？

Question

Is it possible to remape (for example) a 256-colors-gif image into a 128-colors or 64-colors gif image in Python?

I tried it using the imageio library

import imageio

def myfunction(inputgif, outputgif, duration):
  gifimage = imageio.mimread(inputgif)
  for i in range(len(gifimage)):
     gifimage[i] = gifimage[i]/4

  with imageio.get_writer(outputgif, mode='I', duration=duration) as writer:
      for x in range(len(gifimage)):
        writer.append_data(gifimage[x])
  writer.close()

It's working, but, the problem is that the image file still thinks that "his universe" is 256 possible values for the color (from 0 to 255), not from 0 to 64 (since I divided all the values by 4). Which makes the image goes only darker, instead of using a 64 (4 bits) possible colors.

My goal is to obtain a lossy data compression by decreasing number of colors.

Answer 1

The GIF format only supports palette entries on 8 bits.

Even if it supported less, the savings would be marginal: 12.5% for 7 bits, 25% for 6 bits.