forked from josch/img2pdf
Added transparency support for GIFs, palette-based PNGs and grayscale PNGs
This commit is contained in:
Tamás Zahola
Gogs
parent
af5ae5b9b6
commit
64db7909ec
1 changed files with 76 additions and 48 deletions
108
src/img2pdf.py
108
src/img2pdf.py
|
|
@ -85,9 +85,9 @@ FitMode = Enum("FitMode", "into fill exact shrink enlarge")
|
|||
|
||||
PageOrientation = Enum("PageOrientation", "portrait landscape")
|
||||
|
||||
Colorspace = Enum("Colorspace", "RGB L 1 CMYK CMYK;I RGBA P other")
|
||||
Colorspace = Enum("Colorspace", "RGB RGBA L LA 1 CMYK CMYK;I P other")
|
||||
|
||||
ImageFormat = Enum("ImageFormat", "JPEG JPEG2000 CCITTGroup4 PNG TIFF MPO other")
|
||||
ImageFormat = Enum("ImageFormat", "JPEG JPEG2000 CCITTGroup4 PNG GIF TIFF MPO other")
|
||||
|
||||
PageMode = Enum("PageMode", "none outlines thumbs")
|
||||
|
||||
|
|
@ -760,7 +760,7 @@ class pdfdoc(object):
|
|||
artborder=None,
|
||||
iccp=None,
|
||||
):
|
||||
assert color != Colorspace.RGBA or (imgformat == ImageFormat.PNG and smaskdata is not None)
|
||||
assert (color != Colorspace.RGBA and color != Colorspace.LA) or (imgformat == ImageFormat.PNG and smaskdata is not None)
|
||||
|
||||
if self.engine == Engine.pikepdf:
|
||||
PdfArray = pikepdf.Array
|
||||
|
|
@ -780,7 +780,7 @@ class pdfdoc(object):
|
|||
TrueObject = True if self.engine == Engine.pikepdf else PdfObject("true")
|
||||
FalseObject = False if self.engine == Engine.pikepdf else PdfObject("false")
|
||||
|
||||
if color == Colorspace["1"] or color == Colorspace.L:
|
||||
if color == Colorspace["1"] or color == Colorspace.L or color == Colorspace.LA:
|
||||
colorspace = PdfName.DeviceGray
|
||||
elif color == Colorspace.RGB or color == Colorspace.RGBA:
|
||||
colorspace = PdfName.DeviceRGB
|
||||
|
|
@ -819,7 +819,7 @@ class pdfdoc(object):
|
|||
else:
|
||||
iccpdict = PdfDict(stream=convert_load(iccp))
|
||||
iccpdict[PdfName.Alternate] = colorspace
|
||||
if color == Colorspace["1"] or color == Colorspace.L:
|
||||
if color == Colorspace["1"] or color == Colorspace.L or color == Colorspace.LA:
|
||||
iccpdict[PdfName.N] = 1
|
||||
elif color == Colorspace.RGB or color == Colorspace.RGBA:
|
||||
iccpdict[PdfName.N] = 3
|
||||
|
|
@ -872,7 +872,7 @@ class pdfdoc(object):
|
|||
decodeparms[PdfName.Rows] = imgheightpx
|
||||
image[PdfName.DecodeParms] = [decodeparms]
|
||||
elif imgformat is ImageFormat.PNG:
|
||||
if color == Colorspace.RGBA:
|
||||
if smaskdata is not None:
|
||||
if self.engine == Engine.pikepdf:
|
||||
smask = self.writer.make_stream(smaskdata)
|
||||
else:
|
||||
|
|
@ -890,10 +890,10 @@ class pdfdoc(object):
|
|||
# /SMask requires PDF 1.4
|
||||
if self.output_version < "1.4":
|
||||
self.output_version = "1.4"
|
||||
else:
|
||||
|
||||
decodeparms = PdfDict()
|
||||
decodeparms[PdfName.Predictor] = 15
|
||||
if color in [Colorspace.P, Colorspace["1"], Colorspace.L]:
|
||||
if color in [Colorspace.P, Colorspace["1"], Colorspace.L, Colorspace.LA]:
|
||||
decodeparms[PdfName.Colors] = 1
|
||||
else:
|
||||
decodeparms[PdfName.Colors] = 3
|
||||
|
|
@ -1208,8 +1208,19 @@ def get_imgmetadata(
|
|||
ndpi = (int(round(ndpi[0])), int(round(ndpi[1])))
|
||||
ics = imgdata.mode
|
||||
|
||||
if imgformat == ImageFormat.PNG and ics == "RGBA":
|
||||
logger.warning("Image contains an alpha channel which will be stored as a separate soft mask (/SMask) image in PDF.")
|
||||
# GIF and PNG files with transparency are supported
|
||||
if (
|
||||
(imgformat == ImageFormat.PNG or imgformat == ImageFormat.GIF)
|
||||
and (ics in ["RGBA", "LA"] or "transparency" in imgdata.info)
|
||||
):
|
||||
# Must check the IHDR chunk for the bit depth, because PIL would lossily
|
||||
# convert 16-bit RGBA/LA images to 8-bit.
|
||||
if imgformat == ImageFormat.PNG and rawdata != None:
|
||||
depth = rawdata[24]
|
||||
if depth > 8:
|
||||
logger.warning("Image with transparency and a bit depth of %d." % depth)
|
||||
logger.warning("This is unsupported due to PIL limitations.")
|
||||
raise AlphaChannelError("Refusing to work with multiple >8bit channels.")
|
||||
elif (ics in ["LA", "PA", "RGBA"] or "transparency" in imgdata.info):
|
||||
logger.warning("Image contains transparency which cannot be retained in PDF.")
|
||||
logger.warning("img2pdf will not perform a lossy operation.")
|
||||
|
|
@ -1531,21 +1542,12 @@ def read_images(rawdata, colorspace, first_frame_only=False, rot=None):
|
|||
# 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:
|
||||
if imgformat == ImageFormat.PNG and rawdata[28] == 0:
|
||||
color, ndpi, imgwidthpx, imgheightpx, rotation, iccp = get_imgmetadata(
|
||||
imgdata, imgformat, default_dpi, colorspace, rawdata, rot
|
||||
)
|
||||
|
||||
if color == Colorspace.RGBA or rawdata[28] == 0:
|
||||
if color == Colorspace.RGBA:
|
||||
r, g, b, a = imgdata.split()
|
||||
pngdata = zlib.compress(Image.merge("RGB", (r, g, b)).tobytes())
|
||||
smaskdata = zlib.compress(a.tobytes())
|
||||
palette = None
|
||||
else:
|
||||
pngdata, palette = parse_png(rawdata)
|
||||
smaskdata = None
|
||||
|
||||
if color != Colorspace.RGBA and color != Colorspace.LA and "transparency" not in imgdata.info:
|
||||
pngidat, palette = parse_png(rawdata)
|
||||
# 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
|
||||
|
|
@ -1560,8 +1562,8 @@ def read_images(rawdata, colorspace, first_frame_only=False, rot=None):
|
|||
color,
|
||||
ndpi,
|
||||
imgformat,
|
||||
pngdata,
|
||||
smaskdata,
|
||||
pngidat,
|
||||
None,
|
||||
imgwidthpx,
|
||||
imgheightpx,
|
||||
palette,
|
||||
|
|
@ -1703,7 +1705,9 @@ def read_images(rawdata, colorspace, first_frame_only=False, rot=None):
|
|||
color = Colorspace.L
|
||||
elif color in [
|
||||
Colorspace.RGB,
|
||||
Colorspace.RGBA,
|
||||
Colorspace.L,
|
||||
Colorspace.LA,
|
||||
Colorspace.CMYK,
|
||||
Colorspace["CMYK;I"],
|
||||
Colorspace.P,
|
||||
|
|
@ -1734,28 +1738,35 @@ def read_images(rawdata, colorspace, first_frame_only=False, rot=None):
|
|||
)
|
||||
)
|
||||
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
|
||||
# dedicated function applying the Paeth PNG filter to the raw pixel
|
||||
pngbuffer = BytesIO()
|
||||
newimg.save(pngbuffer, format="png")
|
||||
pngidat, palette = parse_png(pngbuffer.getvalue())
|
||||
# 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)
|
||||
if color == Colorspace.RGBA or color == Colorspace.LA or "transparency" in newimg.info:
|
||||
if color == Colorspace.RGBA:
|
||||
newcolor = color
|
||||
r, g, b, a = newimg.split()
|
||||
newimg = Image.merge("RGB", (r, g, b))
|
||||
elif color == Colorspace.LA:
|
||||
newcolor = color
|
||||
l, a = newimg.split()
|
||||
newimg = l
|
||||
else:
|
||||
newcolor = Colorspace.RGBA
|
||||
r, g, b, a = newimg.convert(mode="RGBA").split()
|
||||
newimg = Image.merge("RGB", (r, g, b))
|
||||
|
||||
smaskdata = zlib.compress(a.tobytes())
|
||||
logger.warning("Image contains an alpha channel which will be stored as a separate soft mask (/SMask) image in PDF.")
|
||||
else:
|
||||
newcolor = color
|
||||
smaskdata = None
|
||||
|
||||
pngidat, palette, depth = to_png_data(newimg)
|
||||
logger.debug("read_images() encoded an image as PNG")
|
||||
result.append(
|
||||
(
|
||||
color,
|
||||
newcolor,
|
||||
ndpi,
|
||||
ImageFormat.PNG,
|
||||
pngidat,
|
||||
None,
|
||||
smaskdata,
|
||||
imgwidthpx,
|
||||
imgheightpx,
|
||||
palette,
|
||||
|
|
@ -1769,6 +1780,23 @@ def read_images(rawdata, colorspace, first_frame_only=False, rot=None):
|
|||
cleanup()
|
||||
return result
|
||||
|
||||
def to_png_data(img):
|
||||
# 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()
|
||||
img.save(pngbuffer, format="png")
|
||||
|
||||
pngidat, palette = parse_png(pngbuffer.getvalue())
|
||||
# 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)
|
||||
return pngidat, palette, depth
|
||||
|
||||
# converts a length in pixels to a length in PDF units (1/72 of an inch)
|
||||
def px_to_pt(length, dpi):
|
||||
|
|
|
|||
Loading…
Reference in a new issue