17. Image remap_palette
17.1. Remap_palette
Use the
Image.remap_palette(dest_map, source_palette=None) method to return an image that has been rewritten to reorder the palette.dest_map - A list of indexes into the original palette. e.g. [1,0] would swap a two item palette,
and list(range(256)) is the identity transform. | source_palette - Bytes or None. | remap_palette will change both pixel value and palette (in other words, indexes as pixel values will follow new palette table)
17.2. Remap_palette
The code below converts the image to P, palette mode, gets its colours, reorders them and remaps the palette.
The image before and after remapping should appear the same.
from PIL import Image
def sort_by_neg_zeroth(elem):
return -elem[0]
with Image.open("test_images/lorne.jpg") as im:
im_P = im.convert("P", palette=Image.Palette.ADAPTIVE, colors=16)
im_P.save('Image/Image_remap_palette_before.png')
clrs = im_P.getcolors()
clrs.sort(key=sort_by_neg_zeroth) # sort by occurrence
# [(7776, 4), (7474, 10), (7021, 13), (6466, 6), (5337, 2), (4308, 14), (3991, 12), (3607, 1), (3493, 15), (3179, 5), (2868, 0), (2644, 8), (2527, 3), (1857, 7), (1683, 9), (1305, 11)]
clr_order_for_remap = [c for oc, c in clrs]
# [4, 10, 13, 6, 2, 14, 12, 1, 15, 5, 0, 8, 3, 7, 9, 11]
im_P = im_P.remap_palette(clr_order_for_remap)
im_P.save('Image/Image_remap_palette_after.png')
