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Use PNG predictor for /SMask too

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Tamás Zahola 2021-06-19 01:19:06 +02:00
parent 219dbd2856
commit e6613d3244
1 changed files with 10 additions and 3 deletions
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13
src/img2pdf.py
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@ -885,6 +885,13 @@ class pdfdoc(object):
smask[PdfName.ColorSpace] = PdfName.DeviceGray
smask[PdfName.BitsPerComponent] = depth
decodeparms = PdfDict()
decodeparms[PdfName.Predictor] = 15
decodeparms[PdfName.Colors] = 1
decodeparms[PdfName.Columns] = imgwidthpx
decodeparms[PdfName.BitsPerComponent] = depth
smask[PdfName.DecodeParms] = decodeparms
image[PdfName.SMask] = smask
# /SMask requires PDF 1.4
@ -1752,11 +1759,11 @@ def read_images(rawdata, colorspace, first_frame_only=False, rot=None):
r, g, b, a = newimg.convert(mode="RGBA").split()
newimg = Image.merge("RGB", (r, g, b))
smaskdata = zlib.compress(a.tobytes())
smaskidat, _, _ = to_png_data(a)
logger.warning("Image contains an alpha channel which will be stored as a separate soft mask (/SMask) image in PDF.")
else:
newcolor = color
smaskdata = None
smaskidat = None
pngidat, palette, depth = to_png_data(newimg)
logger.debug("read_images() encoded an image as PNG")
@ -1766,7 +1773,7 @@ def read_images(rawdata, colorspace, first_frame_only=False, rot=None):
ndpi,
ImageFormat.PNG,
pngidat,
smaskdata,
smaskidat,
imgwidthpx,
imgheightpx,
palette,