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
128
src/img2pdf.py
128
src/img2pdf.py
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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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@ -770,71 +772,81 @@ 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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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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while True:
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try:
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imgdata.seek(img_page_count)
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except EOFError:
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break
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if first_frame_only and img_page_count > 0:
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break
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# Everything else has to be encoded
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logging.debug("Converting frame: %d" % img_page_count)
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color, ndpi, imgwidthpx, imgheightpx = get_imgmetadata(
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imgdata, imgformat, default_dpi, colorspace)
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newimg = None
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if color == Colorspace['1']:
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try:
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ccittdata = transcode_monochrome(imgdata)
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imgformat = ImageFormat.CCITTGroup4
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result.append((color, ndpi, imgformat, ccittdata,
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imgwidthpx, imgheightpx))
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img_page_count += 1
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continue
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except Exception as e:
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logging.debug(e)
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logging.debug("Converting colorspace 1 to L")
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newimg = imgdata.convert('L')
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color = Colorspace.L
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elif color in [Colorspace.RGB, Colorspace.L, Colorspace.CMYK,
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Colorspace["CMYK;I"], Colorspace.P]:
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logging.debug("Colorspace is OK: %s", color)
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newimg = imgdata
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elif color in [Colorspace.RGBA, Colorspace.other]:
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logging.debug("Converting colorspace %s to RGB", color)
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newimg = imgdata.convert('RGB')
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color = Colorspace.RGB
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else:
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raise ValueError("unknown colorspace: %s" % color.name)
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# cheapo version to retrieve a PNG encoding of the payload is to
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# just save it with PIL. In the future this could be replaced by
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# dedicated function applying the Paeth PNG filter to the raw pixel
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pngbuffer = BytesIO()
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newimg.save(pngbuffer, format="png")
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pngidat, palette = parse_png(pngbuffer.getvalue())
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imgformat = ImageFormat.PNG
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result.append((color, ndpi, imgformat, pngidat, imgwidthpx,
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imgheightpx, palette))
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img_page_count += 1
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# the python-pil version 2.3.0-1ubuntu3 in Ubuntu does not have the
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# close() method
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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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while True:
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try:
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imgdata.close()
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except AttributeError:
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pass
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im.close()
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return result
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imgdata.seek(img_page_count)
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except EOFError:
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break
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if first_frame_only and img_page_count > 0:
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break
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logging.debug("Converting frame: %d" % img_page_count)
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color, ndpi, imgwidthpx, imgheightpx = get_imgmetadata(
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imgdata, imgformat, default_dpi, colorspace)
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newimg = None
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if color == Colorspace['1']:
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try:
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ccittdata = transcode_monochrome(imgdata)
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imgformat = ImageFormat.CCITTGroup4
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result.append((color, ndpi, imgformat, ccittdata,
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imgwidthpx, imgheightpx))
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img_page_count += 1
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continue
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except Exception as e:
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logging.debug(e)
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logging.debug("Converting colorspace 1 to L")
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newimg = imgdata.convert('L')
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color = Colorspace.L
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elif color in [Colorspace.RGB, Colorspace.L, Colorspace.CMYK,
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Colorspace["CMYK;I"], Colorspace.P]:
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logging.debug("Colorspace is OK: %s", color)
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newimg = imgdata
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elif color in [Colorspace.RGBA, Colorspace.other]:
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logging.debug("Converting colorspace %s to RGB", color)
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newimg = imgdata.convert('RGB')
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color = Colorspace.RGB
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else:
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raise ValueError("unknown colorspace: %s" % color.name)
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# cheapo version to retrieve a PNG encoding of the payload is to
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# just save it with PIL. In the future this could be replaced by
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# dedicated function applying the Paeth PNG filter to the raw pixel
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pngbuffer = BytesIO()
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newimg.save(pngbuffer, format="png")
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pngidat, palette = parse_png(pngbuffer.getvalue())
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imgformat = ImageFormat.PNG
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result.append((color, ndpi, imgformat, pngidat, imgwidthpx,
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imgheightpx, palette))
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img_page_count += 1
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# the python-pil version 2.3.0-1ubuntu3 in Ubuntu does not have the
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# close() method
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try:
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imgdata.close()
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except AttributeError:
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pass
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im.close()
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return result
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# converts a length in pixels to a length in PDF units (1/72 of an inch)
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