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Make optimize a lot safer

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This commit is contained in:
James R. Barlow
2018-04-18 00:20:06 -07:00
parent 78f9f4a266
commit b2f31bec79
1 changed files with 91 additions and 72 deletions
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src/ocrmypdf/_optimize.py
+91 -72
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@@ -72,12 +72,91 @@ def make_img_name(root, xref):
return str(root / '{:08d}.png'.format(xref))
def extract_image(doc, pike, root, log, image, changed_xrefs, jbig2_group,
pngs, jpegs):
if image.Subtype != '/Image':
return
xref = image._objgen[0]
if xref in changed_xrefs:
return # Don't improve same image twice
bpc = image.get('/BitsPerComponent', 8)
filt = image.get('/Filter', pikepdf.Array([]))
cs = image.get('/ColorSpace', '')
w = int(image.Width)
h = int(image.Height)
if filt.type_code == pikepdf.ObjectType.array:
if len(filt) > 1:
log.debug("Skipping multiply filtered {}".format(filt))
return # Not supported: multiple filters
elif len(filt) == 1:
filt = filt[0]
else:
filt = ''
if bpc == 1 and filt != '/JBIG2Decode':
decode_parms = image.get('/DecodeParms')
if filt == '/CCITTFaxDecode':
data = image.read_raw_bytes()
try:
header = generate_ccitt_header(data, w, h, decode_parms)
except ValueError as e:
log.info(e)
return
stream = BytesIO()
stream.write(header)
stream.write(data)
stream.seek(0)
with Image.open(stream) as im:
im.save(make_img_name(root, xref))
else:
return
changed_xrefs.add(xref)
jbig2_group.append(xref)
elif filt == '/JPXDecode':
return
elif filt == '/DCTDecode' and cs in SIMPLE_COLORSPACES:
raw_jpeg = pike._get_object_id(xref, 0)
dp = raw_jpeg.get('/DecodeParms', None)
color_transform = None
try:
color_transform = dp[0].get('/ColorTransform', 1)
except ValueError:
try:
color_transform = dp.get('/ColorTransform', 1)
except ValueError:
pass
if color_transform is not None and color_transform != 1:
return # Don't mess with JPEGs other than YUV
raw_jpeg_data = raw_jpeg.read_raw_bytes()
(root / '{:08d}.jpg'.format(xref)).write_bytes(raw_jpeg_data)
changed_xrefs.add(xref)
jpegs.append(xref)
elif cs in SIMPLE_COLORSPACES:
# For any 'inferior' filter include /FlateDecode we extract
# and recode as /FlateDecode
# raw_png = pike._get_object_id(xref, 0)
# raw_png_data = raw_png.read_raw_bytes()
# (root / '{:08d}.png'.format(xref)).write_bytes(raw_png_data)
pix = fitz.Pixmap(doc, xref)
try:
pix.writePNG(make_img_name(root, xref), savealpha=False)
except RuntimeError as e:
log.error('xref {}'.format(xref))
log.error(e)
return
changed_xrefs.add(xref)
pngs.append(xref)
def extract_images(doc, pike, root, log):
# Extract images we can improve
changed_xrefs = set()
jbig2_groups = defaultdict(lambda: [])
jpegs = []
pngs = []
errors = 0
for pageno, page in enumerate(pike.pages):
group, index = divmod(pageno, PAGE_GROUP_SIZE)
try:
@@ -85,80 +164,20 @@ def extract_images(doc, pike, root, log):
except AttributeError:
continue
for imname, image in dict(xobjs).items():
if image.Subtype != '/Image':
continue
try:
extract_image(
doc, pike, root, log, image, changed_xrefs,
jbig2_groups[group], pngs, jpegs)
except Exception as e:
log.debug("Image {}".format(imname))
log.debug(e)
errors += 1
xref = image._objgen[0]
if xref in changed_xrefs:
continue # Don't improve same image twice
log.debug(
"Optimizable images: JBIG2: {} JPEGs: {} PNGs: {} Errors: {}".format(
len(jbig2_groups), len(jpegs), len(pngs), errors
))
bpc = image.get('/BitsPerComponent', 8)
filt = image.get('/Filter', pikepdf.Array([]))
cs = image.get('/ColorSpace', '')
w = int(image.Width)
h = int(image.Height)
if filt.type_code == pikepdf.ObjectType.array:
if len(filt) > 1:
log.debug("Skipping multiply filtered {}".format(filt))
continue # Not supported: multiple filters
elif len(filt) == 1:
filt = filt[0]
else:
filt = ''
if bpc == 1 and filt != '/JBIG2Decode':
decode_parms = image.get('/DecodeParms')
if filt == '/CCITTFaxDecode':
data = image.read_raw_bytes()
try:
header = generate_ccitt_header(data, w, h, decode_parms)
except ValueError as e:
log.info(e)
continue
stream = BytesIO()
stream.write(header)
stream.write(data)
stream.seek(0)
with Image.open(stream) as im:
im.save(make_img_name(root, xref))
else:
continue
changed_xrefs.add(xref)
jbig2_groups[group].append(xref)
elif filt == '/JPXDecode':
continue
elif filt == '/DCTDecode' and cs in SIMPLE_COLORSPACES:
raw_jpeg = pike._get_object_id(xref, 0)
dp = raw_jpeg.get('/DecodeParms', None)
color_transform = None
try:
color_transform = dp[0].get('/ColorTransform', 1)
except ValueError:
try:
color_transform = dp.get('/ColorTransform', 1)
except ValueError:
pass
if color_transform is not None and color_transform != 1:
continue # Don't mess with JPEGs other than YUV
raw_jpeg_data = raw_jpeg.read_raw_bytes()
(root / '{:08d}.jpg'.format(xref)).write_bytes(raw_jpeg_data)
changed_xrefs.add(xref)
jpegs.append(xref)
elif cs in SIMPLE_COLORSPACES:
# For any 'inferior' filter include /FlateDecode we extract
# and recode as /FlateDecode
# raw_png = pike._get_object_id(xref, 0)
# raw_png_data = raw_png.read_raw_bytes()
# (root / '{:08d}.png'.format(xref)).write_bytes(raw_png_data)
pix = fitz.Pixmap(doc, xref)
try:
pix.writePNG(make_img_name(root, xref), savealpha=False)
except RuntimeError as e:
log.error('page {} xref {}'.format(pageno, xref))
log.error(e)
continue
changed_xrefs.add(xref)
pngs.append(xref)
return changed_xrefs, jbig2_groups, jpegs, pngs