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Fix filter type 3 and 4 byte range

This commit is contained in:
Juan Pablo Gaviria 2016-08-12 08:35:18 -05:00
parent 60dff8d785
commit 60abb83056
1 changed files with 6 additions and 5 deletions
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11
PyPDF2/filters.py
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@ -139,14 +139,15 @@ class FlateDecode(object):
for i in range(1, rowlength):
rowdata[i] = (rowdata[i] + prev_rowdata[i]) % 256
elif filterByte == 3:
for i in range(2, rowlength):
floor = math.floor(rowdata[i-1] + prev_rowdata[i])/2
for i in range(1, rowlength):
left = rowdata[i-1] if i > 1 else 0
floor = math.floor(left + prev_rowdata[i])/2
rowdata[i] = (rowdata[i] + int(floor)) % 256
elif filterByte == 4:
for i in range(2, rowlength):
left = rowdata[i - 1]
for i in range(1, rowlength):
left = rowdata[i - 1] if i > 1 else 0
up = prev_rowdata[i]
up_left = prev_rowdata[i - 1]
up_left = prev_rowdata[i - 1] if i > 1 else 0
paeth = paethPredictor(left, up, up_left)
rowdata[i] = (rowdata[i] + paeth) % 256
else: