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figure out optimal DPI for pdf page conversion

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xenofem 2024-08-04 01:18:18 -04:00
parent 6a8c8c0f1d
commit 8f798e8c21
1 changed files with 20 additions and 1 deletions
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21
dlibrary/dlibrary.py
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@ -779,6 +779,25 @@ def display_sixel_pixmap(pixmap_bytes):
finally:
sixel_output_unref(output)
def naive_convert_page(page):
return { 'ext': 'png', 'image': page.get_pixmap(dpi=PDF_CONVERSION_DPI).tobytes('png') }
def convert_page(pdf, page):
xref = get_displayed_image_xref(page)
if xref is None:
debug('Page has multiple images, converting with naive DPI approach')
return naive_convert_page(page)
image_rect = page.get_image_rects(xref)[0]
image = extract_image(pdf, xref)
scale_factor = image['width'] / image_rect.width
if scale_factor < PDF_CONVERSION_DPI / 72:
debug(f'Image scale factor is lower than {PDF_CONVERSION_DPI}dpi, using higher dpi instead')
return naive_convert_page(page)
debug(f'Page has single image, converting with scale factor {scale_factor}')
return { 'ext': 'png', 'image': page.get_pixmap(matrix=fitz.Matrix(scale_factor, scale_factor)).tobytes('png') }
def pdf_image_extractors(pdf, strategy):
print(f'0/{pdf.page_count} pages analyzed...', end='')
image_extractors = []
@ -796,7 +815,7 @@ def pdf_image_extractors(pdf, strategy):
if choice.lower().startswith('c'):
if choice == strategy:
print(f'Converting page {idx+1}')
image_extractors.append(lambda p=page: { 'ext': 'png', 'image': p.get_pixmap(dpi=PDF_CONVERSION_DPI).tobytes('png') })
image_extractors.append(lambda p=pdf, pp=page: convert_page(p, pp))
break
if xref is not None and (choice.lower().startswith('x') or choice.lower() == 'extract'):
if choice == strategy: