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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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Johannes 'josch' Schauer 6 years ago
parent 53685934f9
commit ccca845606
Signed by untrusted user: josch
GPG Key ID: F2CBA5C78FBD83E1
1 changed files with 27 additions and 35 deletions
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62
src/img2pdf.py
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@ -409,7 +409,8 @@ class pdfdoc(object):
def add_imagepage(self, color, imgwidthpx, imgheightpx, imgformat, imgdata,
imgwidthpdf, imgheightpdf, imgxpdf, imgypdf, pagewidth,
pageheight, userunit=None, palette=None, inverted=False):
pageheight, userunit=None, palette=None, inverted=False,
depth=0):
if self.with_pdfrw:
from pdfrw import PdfDict, PdfName, PdfObject, PdfString
from pdfrw.py23_diffs import convert_load
@ -456,21 +457,7 @@ class pdfdoc(object):
image[PdfName.Width] = imgwidthpx
image[PdfName.Height] = imgheightpx
image[PdfName.ColorSpace] = colorspace
# hardcoded as PIL doesn't provide bits for non-jpeg formats
if imgformat is ImageFormat.CCITTGroup4:
image[PdfName.BitsPerComponent] = 1
else:
if color == Colorspace['1']:
image[PdfName.BitsPerComponent] = 1
elif color == Colorspace.P:
if len(palette) <= 2**1:
image[PdfName.BitsPerComponent] = 1
elif len(palette) <= 2**4:
image[PdfName.BitsPerComponent] = 4
else:
image[PdfName.BitsPerComponent] = 8
else:
image[PdfName.BitsPerComponent] = 8
image[PdfName.BitsPerComponent] = depth
if color == Colorspace['CMYK;I']:
# Inverts all four channels
@ -496,17 +483,7 @@ class pdfdoc(object):
else:
decodeparms[PdfName.Colors] = 3
decodeparms[PdfName.Columns] = imgwidthpx
if color == Colorspace['1']:
decodeparms[PdfName.BitsPerComponent] = 1
elif color == Colorspace.P:
if len(palette) <= 2**1:
decodeparms[PdfName.BitsPerComponent] = 1
elif len(palette) <= 2**4:
decodeparms[PdfName.BitsPerComponent] = 4
else:
decodeparms[PdfName.BitsPerComponent] = 8
else:
decodeparms[PdfName.BitsPerComponent] = 8
decodeparms[PdfName.BitsPerComponent] = depth
image[PdfName.DecodeParms] = decodeparms
text = ("q\n%0.4f 0 0 %0.4f %0.4f %0.4f cm\n/Im0 Do\nQ" %
@ -843,7 +820,7 @@ def read_images(rawdata, colorspace, first_frame_only=False):
im.close()
logging.debug("read_images() embeds a JPEG")
return [(color, ndpi, imgformat, rawdata, imgwidthpx, imgheightpx, [],
False)]
False, 8)]
# We can directly embed the IDAT chunk of PNG images if the PNG is not
# interlaced
@ -857,9 +834,16 @@ def read_images(rawdata, colorspace, first_frame_only=False):
imgdata, imgformat, default_dpi, colorspace, rawdata)
pngidat, palette = parse_png(rawdata)
im.close()
# PIL does not provide the information about the original bits per
# sample. Thus, we retrieve that info manually by looking at byte 9 in
# the IHDR chunk. We know where to find that in the file because the
# IHDR chunk must be the first chunk
depth = rawdata[24]
if depth not in [1, 2, 4, 8, 16]:
raise ValueError("invalid bit depth: %d" % depth)
logging.debug("read_images() embeds a PNG")
return [(color, ndpi, imgformat, pngidat, imgwidthpx, imgheightpx,
palette, False)]
palette, False, depth)]
# If our input is not JPEG or PNG, then we might have a format that
# supports multiple frames (like TIFF or GIF), so we need a loop to
@ -920,7 +904,7 @@ def read_images(rawdata, colorspace, first_frame_only=False):
raise ValueError("unsupported FillOrder: %d" % fillorder)
logging.debug("read_images() embeds a TIFF")
result.append((color, ndpi, ImageFormat.CCITTGroup4, rawdata,
imgwidthpx, imgheightpx, [], inverted))
imgwidthpx, imgheightpx, [], inverted, 1))
img_page_count += 1
continue
@ -937,7 +921,7 @@ def read_images(rawdata, colorspace, first_frame_only=False):
logging.debug(
"read_images() encoded a B/W image as CCITT group 4")
result.append((color, ndpi, imgformat, ccittdata,
imgwidthpx, imgheightpx, [], False))
imgwidthpx, imgheightpx, [], False, 1))
img_page_count += 1
continue
except Exception as e:
@ -958,7 +942,7 @@ def read_images(rawdata, colorspace, first_frame_only=False):
imggz = zlib.compress(newimg.tobytes())
logging.debug("read_images() encoded CMYK with flate compression")
result.append((color, ndpi, imgformat, imggz, imgwidthpx,
imgheightpx, [], False))
imgheightpx, [], False, 8))
else:
# 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
@ -967,9 +951,17 @@ def read_images(rawdata, colorspace, first_frame_only=False):
newimg.save(pngbuffer, format="png")
pngidat, palette = parse_png(pngbuffer.getvalue())
imgformat = ImageFormat.PNG
# PIL does not provide the information about the original bits per
# sample. Thus, we retrieve that info manually by looking at byte 9 in
# the IHDR chunk. We know where to find that in the file because the
# IHDR chunk must be the first chunk
pngbuffer.seek(24)
depth = ord(pngbuffer.read(1))
if depth not in [1, 2, 4, 8, 16]:
raise ValueError("invalid bit depth: %d" % depth)
logging.debug("read_images() encoded an image as PNG")
result.append((color, ndpi, imgformat, pngidat, imgwidthpx,
imgheightpx, palette, False))
imgheightpx, palette, False, depth))
img_page_count += 1
# the python-pil version 2.3.0-1ubuntu3 in Ubuntu does not have the
# close() method
@ -1285,7 +1277,7 @@ def convert(*images, **kwargs):
rawdata = img
for color, ndpi, imgformat, imgdata, imgwidthpx, imgheightpx, \
palette, inverted in read_images(
palette, inverted, depth in read_images(
rawdata, kwargs['colorspace'], kwargs['first_frame_only']):
pagewidth, pageheight, imgwidthpdf, imgheightpdf = \
kwargs['layout_fun'](imgwidthpx, imgheightpx, ndpi)
@ -1310,7 +1302,7 @@ def convert(*images, **kwargs):
pdf.add_imagepage(color, imgwidthpx, imgheightpx, imgformat,
imgdata, imgwidthpdf, imgheightpdf, imgxpdf,
imgypdf, pagewidth, pageheight, userunit,
palette, inverted)
palette, inverted, depth)
if kwargs['outputstream']:
pdf.tostream(kwargs['outputstream'])

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