forked from josch/img2pdf
Interlaced PNGs cannot be directly embedded but have to be re-encoded
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1 changed files with 70 additions and 58 deletions
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@ -759,6 +759,8 @@ def read_images(rawdata, colorspace, first_frame_only=False):
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# depending on the input format, determine whether to pass the raw
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# image or the zlib compressed color information
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# JPEG and JPEG2000 can be embedded into the PDF as-is
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if imgformat == ImageFormat.JPEG or imgformat == ImageFormat.JPEG2000:
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color, ndpi, imgwidthpx, imgheightpx = get_imgmetadata(
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imgdata, imgformat, default_dpi, colorspace, rawdata)
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@ -770,12 +772,22 @@ def read_images(rawdata, colorspace, first_frame_only=False):
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raise JpegColorspaceError("jpeg can't have an alpha channel")
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im.close()
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return [(color, ndpi, imgformat, rawdata, imgwidthpx, imgheightpx, [])]
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elif imgformat == ImageFormat.PNG:
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# We can directly embed the IDAT chunk of PNG images if the PNG is not
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# interlaced
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#
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# PIL does not provide the information whether a PNG was stored interlaced
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# or not. Thus, we retrieve that info manually by looking at byte 13 in the
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# IHDR chunk. We know where to find that in the file because the IHDR chunk
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# must be the first chunk.
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if imgformat == ImageFormat.PNG and rawdata[28] == 0:
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color, ndpi, imgwidthpx, imgheightpx = get_imgmetadata(
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imgdata, imgformat, default_dpi, colorspace, rawdata)
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pngidat, palette = parse_png(rawdata)
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return [(color, ndpi, imgformat, pngidat, imgwidthpx, imgheightpx, palette)]
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else:
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# Everything else has to be encoded
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result = []
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img_page_count = 0
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# loop through all frames of the image (example: multipage TIFF)
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