src/img2pdf.py: Read bits per sample from PNG to support PNG images with 1, 2, 4 or 16 bits per sample
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1 changed files with 27 additions and 35 deletions
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@ -409,7 +409,8 @@ class pdfdoc(object):
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def add_imagepage(self, color, imgwidthpx, imgheightpx, imgformat, imgdata,
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imgwidthpdf, imgheightpdf, imgxpdf, imgypdf, pagewidth,
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pageheight, userunit=None, palette=None, inverted=False):
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pageheight, userunit=None, palette=None, inverted=False,
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depth=0):
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if self.with_pdfrw:
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from pdfrw import PdfDict, PdfName, PdfObject, PdfString
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from pdfrw.py23_diffs import convert_load
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@ -456,21 +457,7 @@ class pdfdoc(object):
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image[PdfName.Width] = imgwidthpx
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image[PdfName.Height] = imgheightpx
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image[PdfName.ColorSpace] = colorspace
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# hardcoded as PIL doesn't provide bits for non-jpeg formats
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if imgformat is ImageFormat.CCITTGroup4:
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image[PdfName.BitsPerComponent] = 1
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else:
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if color == Colorspace['1']:
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image[PdfName.BitsPerComponent] = 1
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elif color == Colorspace.P:
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if len(palette) <= 2**1:
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image[PdfName.BitsPerComponent] = 1
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elif len(palette) <= 2**4:
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image[PdfName.BitsPerComponent] = 4
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else:
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image[PdfName.BitsPerComponent] = 8
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else:
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image[PdfName.BitsPerComponent] = 8
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image[PdfName.BitsPerComponent] = depth
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if color == Colorspace['CMYK;I']:
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# Inverts all four channels
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@ -496,17 +483,7 @@ class pdfdoc(object):
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else:
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decodeparms[PdfName.Colors] = 3
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decodeparms[PdfName.Columns] = imgwidthpx
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if color == Colorspace['1']:
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decodeparms[PdfName.BitsPerComponent] = 1
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elif color == Colorspace.P:
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if len(palette) <= 2**1:
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decodeparms[PdfName.BitsPerComponent] = 1
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elif len(palette) <= 2**4:
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decodeparms[PdfName.BitsPerComponent] = 4
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else:
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decodeparms[PdfName.BitsPerComponent] = 8
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else:
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decodeparms[PdfName.BitsPerComponent] = 8
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decodeparms[PdfName.BitsPerComponent] = depth
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image[PdfName.DecodeParms] = decodeparms
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text = ("q\n%0.4f 0 0 %0.4f %0.4f %0.4f cm\n/Im0 Do\nQ" %
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@ -843,7 +820,7 @@ def read_images(rawdata, colorspace, first_frame_only=False):
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im.close()
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logging.debug("read_images() embeds a JPEG")
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return [(color, ndpi, imgformat, rawdata, imgwidthpx, imgheightpx, [],
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False)]
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False, 8)]
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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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@ -857,9 +834,16 @@ def read_images(rawdata, colorspace, first_frame_only=False):
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imgdata, imgformat, default_dpi, colorspace, rawdata)
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pngidat, palette = parse_png(rawdata)
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im.close()
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# PIL does not provide the information about the original bits per
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# sample. Thus, we retrieve that info manually by looking at byte 9 in
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# the IHDR chunk. We know where to find that in the file because the
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# IHDR chunk must be the first chunk
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depth = rawdata[24]
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if depth not in [1, 2, 4, 8, 16]:
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raise ValueError("invalid bit depth: %d" % depth)
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logging.debug("read_images() embeds a PNG")
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return [(color, ndpi, imgformat, pngidat, imgwidthpx, imgheightpx,
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palette, False)]
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palette, False, depth)]
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# If our input is not JPEG or PNG, then we might have a format that
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# supports multiple frames (like TIFF or GIF), so we need a loop to
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@ -920,7 +904,7 @@ def read_images(rawdata, colorspace, first_frame_only=False):
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raise ValueError("unsupported FillOrder: %d" % fillorder)
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logging.debug("read_images() embeds a TIFF")
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result.append((color, ndpi, ImageFormat.CCITTGroup4, rawdata,
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imgwidthpx, imgheightpx, [], inverted))
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imgwidthpx, imgheightpx, [], inverted, 1))
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img_page_count += 1
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continue
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@ -937,7 +921,7 @@ def read_images(rawdata, colorspace, first_frame_only=False):
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logging.debug(
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"read_images() encoded a B/W image as CCITT group 4")
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result.append((color, ndpi, imgformat, ccittdata,
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imgwidthpx, imgheightpx, [], False))
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imgwidthpx, imgheightpx, [], False, 1))
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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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@ -958,7 +942,7 @@ def read_images(rawdata, colorspace, first_frame_only=False):
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imggz = zlib.compress(newimg.tobytes())
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logging.debug("read_images() encoded CMYK with flate compression")
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result.append((color, ndpi, imgformat, imggz, imgwidthpx,
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imgheightpx, [], False))
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imgheightpx, [], False, 8))
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else:
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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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@ -967,9 +951,17 @@ def read_images(rawdata, colorspace, first_frame_only=False):
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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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# PIL does not provide the information about the original bits per
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# sample. Thus, we retrieve that info manually by looking at byte 9 in
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# the IHDR chunk. We know where to find that in the file because the
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# IHDR chunk must be the first chunk
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pngbuffer.seek(24)
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depth = ord(pngbuffer.read(1))
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if depth not in [1, 2, 4, 8, 16]:
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raise ValueError("invalid bit depth: %d" % depth)
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logging.debug("read_images() encoded an image as PNG")
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result.append((color, ndpi, imgformat, pngidat, imgwidthpx,
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imgheightpx, palette, False))
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imgheightpx, palette, False, depth))
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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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@ -1285,7 +1277,7 @@ def convert(*images, **kwargs):
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rawdata = img
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for color, ndpi, imgformat, imgdata, imgwidthpx, imgheightpx, \
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palette, inverted in read_images(
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palette, inverted, depth in read_images(
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rawdata, kwargs['colorspace'], kwargs['first_frame_only']):
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pagewidth, pageheight, imgwidthpdf, imgheightpdf = \
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kwargs['layout_fun'](imgwidthpx, imgheightpx, ndpi)
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@ -1310,7 +1302,7 @@ def convert(*images, **kwargs):
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pdf.add_imagepage(color, imgwidthpx, imgheightpx, imgformat,
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imgdata, imgwidthpdf, imgheightpdf, imgxpdf,
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imgypdf, pagewidth, pageheight, userunit,
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palette, inverted)
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palette, inverted, depth)
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if kwargs['outputstream']:
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pdf.tostream(kwargs['outputstream'])
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