James R. Barlow
6b9adef684
...except that Ghostscript will sometimes turn out of line images into inline images on its own, possibly if file size is small.
138 lines
4.1 KiB
Python
138 lines
4.1 KiB
Python
#!/usr/bin/env python3
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#
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from subprocess import Popen, PIPE
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from decimal import Decimal, getcontext
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import re
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import sys
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import PyPDF2 as pypdf
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FRIENDLY_COLORSPACE = {
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'/DeviceGray': 'gray',
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'/CalGray': 'gray',
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'/DeviceRGB': 'rgb',
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'/CalRGB': 'rgb',
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'/DeviceCMYK': 'cmyk',
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'/Lab': 'lab',
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'/ICCBased': 'icc',
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'/Indexed': 'index',
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'/Separation': 'sep',
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'/DeviceN': 'devn',
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'/Pattern': '-'
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}
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FRIENDLY_ENCODING = {
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'/CCITTFaxDecode': 'ccitt',
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'/DCTDecode': 'jpeg',
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'/JPXDecode': 'jpx',
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'/JBIG2Decode': 'jbig2',
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}
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FRIENDLY_COMP = {
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'gray': 1,
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'rgb': 3,
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'cmyk': 4,
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'lab': 3,
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}
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def _page_has_inline_images(page):
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# PDF always uses \r\n for separator regardless of platform
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# Really basic heuristic that might trigger the odd false positive
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# This is only finds the first image and is not quite spec compliant
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contents = page.getContents()
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data = contents.getData()
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begin_image, image_data, end_image = False, False, False
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for data in re.split(b'\s+', data):
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if data == b'BI':
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begin_image = True
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elif data == b'ID':
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image_data = True
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elif data == b'EI':
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end_image = True
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if all((begin_image, image_data, end_image)):
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return True
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def _find_page_images(page, pageinfo):
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try:
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page['/Resources']['/XObject']
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except KeyError:
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return
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# Look for XObject (out of line images)
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for xobj in page['/Resources']['/XObject']:
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# PyPDF2 returns the keys as an iterator
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pdfimage = page['/Resources']['/XObject'][xobj]
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if pdfimage['/Subtype'] != '/Image':
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continue
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if '/ImageMask' in pdfimage:
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if pdfimage['/ImageMask']:
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continue
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image = {}
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image['width'] = pdfimage['/Width']
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image['height'] = pdfimage['/Height']
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image['bpc'] = pdfimage['/BitsPerComponent']
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if '/Filter' in pdfimage:
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filter_ = pdfimage['/Filter']
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if isinstance(filter_, pypdf.generic.ArrayObject):
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filter_ = filter_[0]
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image['enc'] = FRIENDLY_ENCODING.get(filter_, 'image')
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else:
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image['enc'] = 'image'
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if '/ColorSpace' in pdfimage:
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cs = pdfimage['/ColorSpace']
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if isinstance(cs, pypdf.generic.ArrayObject):
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cs = cs[0]
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image['color'] = FRIENDLY_COLORSPACE.get(cs, '-')
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else:
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image['color'] = 'jpx' if image['enc'] == 'jpx' else '?'
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image['comp'] = FRIENDLY_COMP.get(image['color'], '?')
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image['dpi_w'] = image['width'] / pageinfo['width_inches']
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image['dpi_h'] = image['height'] / pageinfo['height_inches']
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image['dpi'] = (image['dpi_w'] * image['dpi_h']) ** Decimal(0.5)
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yield image
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def _pdf_get_pageinfo(infile, page: int):
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pageinfo = {}
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pageinfo['pageno'] = page
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pageinfo['images'] = []
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pdf = pypdf.PdfFileReader(infile)
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page = pdf.pages[page - 1]
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text = page.extractText()
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pageinfo['has_text'] = (text.strip() != '')
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width_pt = page['/MediaBox'][2] - page['/MediaBox'][0]
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height_pt = page['/MediaBox'][3] - page['/MediaBox'][1]
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pageinfo['width_inches'] = width_pt / Decimal(72.0)
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pageinfo['height_inches'] = height_pt / Decimal(72.0)
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pageinfo['images'] = [im for im in _find_page_images(page, pageinfo)]
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# Look for inline images
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if _page_has_inline_images(page):
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raise NotImplementedError(
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"Warning: input PDF contains inline images - not supported")
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if pageinfo['images']:
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xres = max(image['dpi_w'] for image in pageinfo['images'])
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yres = max(image['dpi_h'] for image in pageinfo['images'])
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pageinfo['xres'], pageinfo['yres'] = xres, yres
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pageinfo['width_pixels'] = \
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int(round(xres * pageinfo['width_inches']))
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pageinfo['height_pixels'] = \
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int(round(yres * pageinfo['height_inches']))
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return pageinfo
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def pdf_get_all_pageinfo(infile):
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pdf = pypdf.PdfFileReader(infile)
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getcontext().prec = 6
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return [_pdf_get_pageinfo(infile, n) for n in range(pdf.numPages)]
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