Interlaced PNGs cannot be directly embedded but have to be re-encoded
This commit is contained in:
parent
7244d2c6ed
commit
d9a6c9db03
GPG key ID:
F2CBA5C78FBD83E1
1 changed files with 70 additions and 58 deletions
128
src/img2pdf.py
128
src/img2pdf.py
|
|
@ -759,6 +759,8 @@ def read_images(rawdata, colorspace, first_frame_only=False):
|
|||
|
||||
# depending on the input format, determine whether to pass the raw
|
||||
# image or the zlib compressed color information
|
||||
|
||||
# JPEG and JPEG2000 can be embedded into the PDF as-is
|
||||
if imgformat == ImageFormat.JPEG or imgformat == ImageFormat.JPEG2000:
|
||||
color, ndpi, imgwidthpx, imgheightpx = get_imgmetadata(
|
||||
imgdata, imgformat, default_dpi, colorspace, rawdata)
|
||||
|
|
@ -770,71 +772,81 @@ def read_images(rawdata, colorspace, first_frame_only=False):
|
|||
raise JpegColorspaceError("jpeg can't have an alpha channel")
|
||||
im.close()
|
||||
return [(color, ndpi, imgformat, rawdata, imgwidthpx, imgheightpx, [])]
|
||||
elif imgformat == ImageFormat.PNG:
|
||||
|
||||
# We can directly embed the IDAT chunk of PNG images if the PNG is not
|
||||
# interlaced
|
||||
#
|
||||
# PIL does not provide the information whether a PNG was stored interlaced
|
||||
# or not. Thus, we retrieve that info manually by looking at byte 13 in the
|
||||
# IHDR chunk. We know where to find that in the file because the IHDR chunk
|
||||
# must be the first chunk.
|
||||
if imgformat == ImageFormat.PNG and rawdata[28] == 0:
|
||||
color, ndpi, imgwidthpx, imgheightpx = get_imgmetadata(
|
||||
imgdata, imgformat, default_dpi, colorspace, rawdata)
|
||||
pngidat, palette = parse_png(rawdata)
|
||||
return [(color, ndpi, imgformat, pngidat, imgwidthpx, imgheightpx, palette)]
|
||||
else:
|
||||
result = []
|
||||
img_page_count = 0
|
||||
# loop through all frames of the image (example: multipage TIFF)
|
||||
while True:
|
||||
try:
|
||||
imgdata.seek(img_page_count)
|
||||
except EOFError:
|
||||
break
|
||||
|
||||
if first_frame_only and img_page_count > 0:
|
||||
break
|
||||
# Everything else has to be encoded
|
||||
|
||||
logging.debug("Converting frame: %d" % img_page_count)
|
||||
|
||||
color, ndpi, imgwidthpx, imgheightpx = get_imgmetadata(
|
||||
imgdata, imgformat, default_dpi, colorspace)
|
||||
|
||||
newimg = None
|
||||
if color == Colorspace['1']:
|
||||
try:
|
||||
ccittdata = transcode_monochrome(imgdata)
|
||||
imgformat = ImageFormat.CCITTGroup4
|
||||
result.append((color, ndpi, imgformat, ccittdata,
|
||||
imgwidthpx, imgheightpx))
|
||||
img_page_count += 1
|
||||
continue
|
||||
except Exception as e:
|
||||
logging.debug(e)
|
||||
logging.debug("Converting colorspace 1 to L")
|
||||
newimg = imgdata.convert('L')
|
||||
color = Colorspace.L
|
||||
elif color in [Colorspace.RGB, Colorspace.L, Colorspace.CMYK,
|
||||
Colorspace["CMYK;I"], Colorspace.P]:
|
||||
logging.debug("Colorspace is OK: %s", color)
|
||||
newimg = imgdata
|
||||
elif color in [Colorspace.RGBA, Colorspace.other]:
|
||||
logging.debug("Converting colorspace %s to RGB", color)
|
||||
newimg = imgdata.convert('RGB')
|
||||
color = Colorspace.RGB
|
||||
else:
|
||||
raise ValueError("unknown colorspace: %s" % color.name)
|
||||
# cheapo version to retrieve a PNG encoding of the payload is to
|
||||
# just save it with PIL. In the future this could be replaced by
|
||||
# dedicated function applying the Paeth PNG filter to the raw pixel
|
||||
pngbuffer = BytesIO()
|
||||
newimg.save(pngbuffer, format="png")
|
||||
pngidat, palette = parse_png(pngbuffer.getvalue())
|
||||
imgformat = ImageFormat.PNG
|
||||
result.append((color, ndpi, imgformat, pngidat, imgwidthpx,
|
||||
imgheightpx, palette))
|
||||
img_page_count += 1
|
||||
# the python-pil version 2.3.0-1ubuntu3 in Ubuntu does not have the
|
||||
# close() method
|
||||
result = []
|
||||
img_page_count = 0
|
||||
# loop through all frames of the image (example: multipage TIFF)
|
||||
while True:
|
||||
try:
|
||||
imgdata.close()
|
||||
except AttributeError:
|
||||
pass
|
||||
im.close()
|
||||
return result
|
||||
imgdata.seek(img_page_count)
|
||||
except EOFError:
|
||||
break
|
||||
|
||||
if first_frame_only and img_page_count > 0:
|
||||
break
|
||||
|
||||
logging.debug("Converting frame: %d" % img_page_count)
|
||||
|
||||
color, ndpi, imgwidthpx, imgheightpx = get_imgmetadata(
|
||||
imgdata, imgformat, default_dpi, colorspace)
|
||||
|
||||
newimg = None
|
||||
if color == Colorspace['1']:
|
||||
try:
|
||||
ccittdata = transcode_monochrome(imgdata)
|
||||
imgformat = ImageFormat.CCITTGroup4
|
||||
result.append((color, ndpi, imgformat, ccittdata,
|
||||
imgwidthpx, imgheightpx))
|
||||
img_page_count += 1
|
||||
continue
|
||||
except Exception as e:
|
||||
logging.debug(e)
|
||||
logging.debug("Converting colorspace 1 to L")
|
||||
newimg = imgdata.convert('L')
|
||||
color = Colorspace.L
|
||||
elif color in [Colorspace.RGB, Colorspace.L, Colorspace.CMYK,
|
||||
Colorspace["CMYK;I"], Colorspace.P]:
|
||||
logging.debug("Colorspace is OK: %s", color)
|
||||
newimg = imgdata
|
||||
elif color in [Colorspace.RGBA, Colorspace.other]:
|
||||
logging.debug("Converting colorspace %s to RGB", color)
|
||||
newimg = imgdata.convert('RGB')
|
||||
color = Colorspace.RGB
|
||||
else:
|
||||
raise ValueError("unknown colorspace: %s" % color.name)
|
||||
# cheapo version to retrieve a PNG encoding of the payload is to
|
||||
# just save it with PIL. In the future this could be replaced by
|
||||
# dedicated function applying the Paeth PNG filter to the raw pixel
|
||||
pngbuffer = BytesIO()
|
||||
newimg.save(pngbuffer, format="png")
|
||||
pngidat, palette = parse_png(pngbuffer.getvalue())
|
||||
imgformat = ImageFormat.PNG
|
||||
result.append((color, ndpi, imgformat, pngidat, imgwidthpx,
|
||||
imgheightpx, palette))
|
||||
img_page_count += 1
|
||||
# the python-pil version 2.3.0-1ubuntu3 in Ubuntu does not have the
|
||||
# close() method
|
||||
try:
|
||||
imgdata.close()
|
||||
except AttributeError:
|
||||
pass
|
||||
im.close()
|
||||
return result
|
||||
|
||||
|
||||
# converts a length in pixels to a length in PDF units (1/72 of an inch)
|
||||
|
|
|
|||
Loading…
Reference in a new issue