add support for MPO images (closes: #93)

This commit is contained in:
Johannes Schauer Marin Rodrigues 2021-04-12 22:57:51 +02:00
parent cd1088a5a9
commit d29c596fe7
Signed by untrusted user: josch
GPG key ID: F2CBA5C78FBD83E1

View file

@ -85,7 +85,7 @@ PageOrientation = Enum("PageOrientation", "portrait landscape")
Colorspace = Enum("Colorspace", "RGB L 1 CMYK CMYK;I RGBA P other")
ImageFormat = Enum("ImageFormat", "JPEG JPEG2000 CCITTGroup4 PNG TIFF other")
ImageFormat = Enum("ImageFormat", "JPEG JPEG2000 CCITTGroup4 PNG TIFF MPO other")
PageMode = Enum("PageMode", "none outlines thumbs")
@ -1402,6 +1402,61 @@ def read_images(rawdata, colorspace, first_frame_only=False):
)
]
# The MPO format is multiple JPEG images concatenated together
# we use the offset and size information to dissect the MPO into its
# individual JPEG images and then embed those into the PDF individually.
#
# The downside is, that this truncates the first JPEG as the MPO metadata
# will still be in it but the referenced images are chopped off. We still
# do it that way instead of adding the full MPO as the first image to not
# store duplicate image data.
if imgformat == ImageFormat.MPO:
result = []
img_page_count = 0
for offset, mpent in zip(
imgdata._MpoImageFile__mpoffsets, imgdata.mpinfo[0xB002]
):
if first_frame_only and img_page_count > 0:
break
rawframe = BytesIO(rawdata[offset : offset + mpent["Size"]])
imframe = Image.open(rawframe)
# The first frame contains the data that makes the JPEG a MPO
# Could we thus embed an MPO into another MPO? Lets not support
# such madness ;)
if img_page_count > 0 and imframe.format != "JPEG":
raise Exception("MPO payload must be a JPEG %s", imframe.format)
color, ndpi, imgwidthpx, imgheightpx, rotation, iccp = get_imgmetadata(
imframe, ImageFormat.JPEG, default_dpi, colorspace
)
imframe.close()
rawframe.close()
if color == Colorspace["1"]:
raise JpegColorspaceError("jpeg can't be monochrome")
if color == Colorspace["P"]:
raise JpegColorspaceError("jpeg can't have a color palette")
if color == Colorspace["RGBA"]:
raise JpegColorspaceError("jpeg can't have an alpha channel")
logger.debug("read_images() embeds a JPEG from MPO")
result.append(
(
color,
ndpi,
ImageFormat.JPEG,
rawdata[offset : offset + mpent["Size"]],
imgwidthpx,
imgheightpx,
[],
False,
8,
rotation,
iccp,
)
)
img_page_count += 1
imgdata.close()
im.close()
return result
# We can directly embed the IDAT chunk of PNG images if the PNG is not
# interlaced
#