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identify PDF page image xrefs in a *much* faster and less stupid way than PyMuPDF does it

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xenofem 2024-03-16 01:51:01 -04:00
parent 5378899b2e
commit 435af20e59
1 changed files with 33 additions and 11 deletions
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dlibrary/dlibrary.py
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@ -88,6 +88,9 @@ IRRELEVANT_PDF_BLOCK_REGEX = re.compile(r'\bTCPDF\b', re.I)
MULTIPART_RAR_HEAD_REGEX = re.compile(r'^(.+)\.part0*1\.exe$', re.I) MULTIPART_RAR_HEAD_REGEX = re.compile(r'^(.+)\.part0*1\.exe$', re.I)
MULTIPART_RAR_TAIL_REGEX = re.compile(r'^(.+)\.part0*([^1]|[^0].+)\.rar$', re.I) MULTIPART_RAR_TAIL_REGEX = re.compile(r'^(.+)\.part0*([^1]|[^0].+)\.rar$', re.I)
PDF_REFERENCED_IMAGE_REGEX = re.compile(r'(^|(?<=\s))/(?P<ref_name>\S+)\s+Do($|(?=\s))')
PDF_INLINE_IMAGE_REGEX = re.compile(r'(^|\s)(BI|ID|EI)($|\s)')
debug_mode = False debug_mode = False
def debug(s): def debug(s):
if debug_mode: if debug_mode:
@ -575,6 +578,33 @@ def extract_image(pdf, xref):
pix = fitz.Pixmap(pdf, xref) pix = fitz.Pixmap(pdf, xref)
return { 'ext': 'png', 'image': pix.tobytes('png') } return { 'ext': 'png', 'image': pix.tobytes('png') }
def get_displayed_image_xref(page):
ref_names = []
for content_xref in page.get_contents():
content = page.parent.xref_stream(content_xref).decode('ascii', 'replace')
if PDF_INLINE_IMAGE_REGEX.search(content):
debug('Inline image detected')
return None
for m in PDF_REFERENCED_IMAGE_REGEX.finditer(content):
ref_names.append(m.group('ref_name'))
if len(ref_names) == 0:
debug('Page does not reference any xobjects')
return None
if len(ref_names) > 1:
debug(f'Page references multiple xobjects: {ref_names}')
return None
image_xrefs = [image[0] for image in page.get_images() if image[7] == ref_names[0]]
if len(image_xrefs) == 1:
return image_xrefs[0]
if len(image_xrefs) == 0:
debug(f'No images found matching ref name {ref_names[0]}')
else:
debug(f"Multiple images found matching ref name {ref_names[0]}, that probably shouldn't happen")
return None
def display_sixel_page(page): def display_sixel_page(page):
s = BytesIO() s = BytesIO()
image = Image.open(BytesIO(page.get_pixmap(dpi=PDF_PREVIEW_DPI).tobytes('png'))) image = Image.open(BytesIO(page.get_pixmap(dpi=PDF_PREVIEW_DPI).tobytes('png')))
@ -615,23 +645,15 @@ def display_sixel_page(page):
sixel_output_unref(output) sixel_output_unref(output)
def pdf_images(pdf, strategy): def pdf_images(pdf, strategy):
images_by_page = [(page.get_images(), is_single_image(page)) for page in pdf]
if all(len(images) == 1 and single for (images, single) in images_by_page):
return (extract_image(pdf, images[0][0]) for (images, _) in images_by_page)
print("Checking PDF images the quick way failed, trying the slow way")
print(f'0/{pdf.page_count} pages analyzed...', end='') print(f'0/{pdf.page_count} pages analyzed...', end='')
image_extractors = [] image_extractors = []
for (idx, page) in enumerate(pdf): for (idx, page) in enumerate(pdf):
page_images = page.get_image_info(xrefs=True) xref = get_displayed_image_xref(page)
if len(page_images) == 1 and page_images[0]['xref'] != 0:
xref = page_images[0]['xref']
else:
xref = None
if xref is not None and is_single_image(page): if xref is not None and is_single_image(page):
image_extractors.append(lambda p=pdf, x=xref: extract_image(p, x)) image_extractors.append(lambda p=pdf, x=xref: extract_image(p, x))
else: else:
print(f'\nPage {idx+1}: {len(page_images)} images, {len([img for img in page_images if img["xref"] == 0])} non-xref images, {len(relevant_blocks(page))} total relevant objects') page_images = page.get_image_info()
print(f'\nPage {idx+1}: {len(page_images)} images, {len(relevant_blocks(page))} total relevant objects')
choice = strategy choice = strategy
while True: while True:
if choice.lower().startswith('n'): if choice.lower().startswith('n'):