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Corrected color table size calculation

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This commit is contained in:
Andrew Murray 2019-06-29 19:24:12 +10:00
parent 3e4db05249
commit 97c15a245c
2 changed files with 7 additions and 8 deletions
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2
Tests/test_file_gif.py
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@ -59,7 +59,7 @@ class TestFileGif(PillowTestCase):
return len(test_file.getvalue())
self.assertEqual(test_grayscale(0), 800)
self.assertEqual(test_grayscale(1), 38)
self.assertEqual(test_grayscale(1), 44)
self.assertEqual(test_bilevel(0), 800)
self.assertEqual(test_bilevel(1), 800)

13
src/PIL/GifImagePlugin.py
View File

@ -580,9 +580,6 @@ def _write_local_header(fp, im, offset, flags):
include_color_table = im.encoderinfo.get("include_color_table")
if include_color_table:
palette_bytes = _get_palette_bytes(im)
# If needed, expand palette to minimum size
while(len(palette_bytes) < 9):
palette_bytes = palette_bytes*2
color_table_size = _get_color_table_size(palette_bytes)
if color_table_size:
flags = flags | 128 # local color table flag
@ -693,10 +690,12 @@ def _get_color_table_size(palette_bytes):
# calculate the palette size for the header
import math
color_table_size = int(math.ceil(math.log(len(palette_bytes) // 3, 2))) - 1
if color_table_size < 0:
color_table_size = 0
return color_table_size
if not palette_bytes:
return 0
elif len(palette_bytes) < 9:
return 1
else:
return int(math.ceil(math.log(len(palette_bytes) // 3, 2))) - 1
def _get_header_palette(palette_bytes):