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Add support for inline images

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This commit is contained in:
James R. Barlow
2016-02-26 22:44:28 -08:00
parent 3957a0606c
commit 5cc3adb39a
2 changed files with 78 additions and 58 deletions
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130
ocrmypdf/pageinfo.py
View File

@@ -67,14 +67,14 @@ def euclidean_distance(rowvec1, rowvec2):
ContentsInfo = namedtuple('ContentsInfo',
['raster_settings', 'has_inline_images'])
['raster_settings', 'inline_images'])
def _interpret_contents(contentstream):
operations = contentstream.operations
stack = []
ctm = _matrix_from_shorthand((1, 0, 0, 1, 0, 0))
image_raster_settings = []
has_inline_images = False
inline_images = []
print(operations)
for op in operations:
@@ -91,21 +91,85 @@ def _interpret_contents(contentstream):
image_raster_settings.append(
(image_name, _shorthand_from_matrix(ctm)))
elif command == b'INLINE IMAGE':
# {'settings': {'/BPC': 8, '/H': 8, '/CS': '/RGB', '/F': ['/A85', '/Fl'], '/W': 8}, 'data': b'...'},
has_inline_images = True
settings = operands['settings']
inline_images.append(
(settings, _shorthand_from_matrix(ctm)))
return ContentsInfo(
raster_settings=image_raster_settings,
has_inline_images=has_inline_images)
inline_images=inline_images)
def _get_dpi(ctm_shorthand, image_size):
matrix = _matrix_from_shorthand(ctm_shorthand)
# Corners of the image in untranslated square image space; last
# column is a dummy
corners = [[0, 0, 1],
[1, 0, 1],
[0, 1, 1],
[1, 1, 1]]
# Rotate/translate/scale the corners into PDF coords (1/72")
# ordering of points may change, e.g. if rotation is 180 then
# the point (0, 0) may become the top right
# The row vectors can all be transformed together here by building
# a matrix of them
page_unit_corners = matrix_mult(corners, matrix)
print(matrix)
print(page_unit_corners)
# Calculate the width and height of the rotated image
# the transformation matrix so the corner that was originally
# (1, 1) can be ignored
image_drawn_width = euclidean_distance(
page_unit_corners[0], page_unit_corners[1])
image_drawn_height = euclidean_distance(
page_unit_corners[0], page_unit_corners[2])
print((image_drawn_width, image_drawn_height))
# The scale of the image is pixels per PDF unit (1/72")
scale_w = image_size[0] / image_drawn_width
scale_h = image_size[1] / image_drawn_height
# DPI = scale * 72
dpi_w = scale_w * 72.0
dpi_h = scale_h * 72.0
print((dpi_w, dpi_h))
# If the image is drawn skewed or rotated analyzing its actual
# bounding box is a bit more of headache. This is allowed, but
# rare.
if ctm_shorthand[1] != 0 or ctm_shorthand[2] != 0:
print('image was rotated')
return (dpi_w, dpi_h)
def _find_page_images(page, pageinfo, contentsinfo):
for n, im in enumerate(contentsinfo.inline_images):
print(n)
settings, shorthand = im
image = {}
image['name'] = str('inline-%02d' % n)
image['width'] = settings['/W']
image['height'] = settings['/H']
image['bpc'] = settings['/BPC']
image['color'] = FRIENDLY_COLORSPACE.get(settings['/CS'], '-')
image['comp'] = FRIENDLY_COMP.get(image['color'], '?')
dpi_w, dpi_h = _get_dpi(shorthand, (image['width'], image['height']))
image['dpi_w'], image['dpi_h'] = Decimal(dpi_w), Decimal(dpi_h)
yield image
# Look for XObject (out of line images)
try:
page['/Resources']['/XObject']
except KeyError:
return
# Look for XObject (out of line images)
for xobj in page['/Resources']['/XObject']:
# PyPDF2 returns the keys as an iterator
pdfimage = page['/Resources']['/XObject'][xobj]
@@ -142,49 +206,9 @@ def _find_page_images(page, pageinfo, contentsinfo):
if raster[0] != image['name']:
continue
shorthand = raster[1]
matrix = _matrix_from_shorthand(shorthand)
# Corners of the image in untranslated square image space; last
# column is a dummy
corners = [[0, 0, 1],
[1, 0, 1],
[0, 1, 1],
[1, 1, 1]]
# Rotate/translate/scale the corners into PDF coords (1/72")
# ordering of points may change, e.g. if rotation is 180 then
# the point (0, 0) may become the top right
# The row vectors can all be transformed together here by building
# a matrix of them
page_unit_corners = matrix_mult(corners, matrix)
print(matrix)
print(page_unit_corners)
# Calculate the width and height of the rotated image
# the transformation matrix so the corner that was originally
# (1, 1) can be ignored
image_drawn_width = euclidean_distance(
page_unit_corners[0], page_unit_corners[1])
image_drawn_height = euclidean_distance(
page_unit_corners[0], page_unit_corners[2])
print((image_drawn_width, image_drawn_height))
# The scale of the image is pixels per PDF unit (1/72")
scale_w = image['width'] / image_drawn_width
scale_h = image['height'] / image_drawn_height
# DPI = scale * 72
dpi_w = scale_w * 72.0
dpi_h = scale_h * 72.0
print((dpi_w, dpi_h))
# If the image is drawn skewed or rotated analyzing its actual
# bounding box is a bit more of headache. This is allowed, but
# rare.
if shorthand[1] != 0 or shorthand[2] != 0:
print('image was rotated')
dpi_w, dpi_h = _get_dpi(
shorthand, (image['width'], image['height']))
# When image is used multiple times take the highest DPI it is
# rendered at
@@ -238,16 +262,10 @@ def _pdf_get_pageinfo(infile, pageno: int):
return pageinfo
contentsinfo = _interpret_contents(contentstream)
print(contentsinfo)
pageinfo['images'] = [im for im in _find_page_images(
page, pageinfo, contentsinfo)]
# Look for inline images
if contentsinfo.has_inline_images:
raise NotImplementedError(
"Warning: input PDF contains inline images - not supported")
if pageinfo['images']:
xres = max(image['dpi_w'] for image in pageinfo['images'])
yres = max(image['dpi_h'] for image in pageinfo['images'])

6
tests/test_pageinfo.py
View File

@@ -120,8 +120,10 @@ def test_single_page_inline_image():
pdf.showPage()
pdf.save()
with pytest.raises(NotImplementedError):
pageinfo.pdf_get_all_pageinfo(filename)
pdfinfo = pageinfo.pdf_get_all_pageinfo(filename)
print(pdfinfo)
pdfimage = pdfinfo[0]['images'][0]
assert (pdfimage['dpi_w'] - 8) < 1e-5
def test_jpeg():