josch/img2pdf
3
6
Fork 10
Code Issues 22 Pull requests 5 Projects Releases 3 Wiki Activity

Convert 8-bit PNG & GIF alpha channels to /SMasks in PDF #106

Merged
josch merged 7 commits from tzahola/img2pdf:png-alpha-to-smask into main 2021-08-22 08:08:26 +00:00
Conversation 21 Commits 7 Files changed 2 +10 -3
1 changed files with 10 additions and 3 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files
Showing only changes of commit e6613d3244 - Show all commits

13
src/img2pdf.py
View file

@ -885,6 +885,13 @@ class pdfdoc(object):
smask[PdfName.ColorSpace] = PdfName.DeviceGray smask[PdfName.ColorSpace] = PdfName.DeviceGray
smask[PdfName.BitsPerComponent] = depth smask[PdfName.BitsPerComponent] = depth
decodeparms = PdfDict()
decodeparms[PdfName.Predictor] = 15
decodeparms[PdfName.Colors] = 1
decodeparms[PdfName.Columns] = imgwidthpx
decodeparms[PdfName.BitsPerComponent] = depth
smask[PdfName.DecodeParms] = decodeparms
image[PdfName.SMask] = smask image[PdfName.SMask] = smask
# /SMask requires PDF 1.4 # /SMask requires PDF 1.4
@ -1752,11 +1759,11 @@ def read_images(rawdata, colorspace, first_frame_only=False, rot=None):
r, g, b, a = newimg.convert(mode="RGBA").split() r, g, b, a = newimg.convert(mode="RGBA").split()
newimg = Image.merge("RGB", (r, g, b)) newimg = Image.merge("RGB", (r, g, b))
smaskdata = zlib.compress(a.tobytes()) smaskidat, _, _ = to_png_data(a)
logger.warning("Image contains an alpha channel which will be stored as a separate soft mask (/SMask) image in PDF.") logger.warning("Image contains an alpha channel which will be stored as a separate soft mask (/SMask) image in PDF.")
else: else:
newcolor = color newcolor = color
smaskdata = None smaskidat = None
pngidat, palette, depth = to_png_data(newimg) pngidat, palette, depth = to_png_data(newimg)
logger.debug("read_images() encoded an image as PNG") logger.debug("read_images() encoded an image as PNG")
@ -1766,7 +1773,7 @@ def read_images(rawdata, colorspace, first_frame_only=False, rot=None):
ndpi, ndpi,
ImageFormat.PNG, ImageFormat.PNG,
pngidat, pngidat,
smaskdata, smaskidat,
imgwidthpx, imgwidthpx,
imgheightpx, imgheightpx,
palette, palette,