def test_bbox_from_xywh(self):
self.assertEqual(
bbox_from_xywh({
'x': 100,
'y': 100,
'w': 100,
'h': 100
}), (100, 100, 200, 200))
def estimate_bounds(self, page, page_image, tessapi, zoom=1.0):
"""Get outer bounds of all (existing or detected) regions."""
LOG = getLogger('processor.TesserocrCrop')
all_left = page_image.width
all_top = page_image.height
all_right = 0
all_bottom = 0
LOG.info("Cropping with Tesseract")
tessapi.SetImage(page_image)
# PSM.SPARSE_TEXT: get as much text as possible in no particular order
# PSM.AUTO (default): includes tables (dangerous)
# PSM.SPARSE_TEXT_OSD: sparse but all orientations
tessapi.SetPageSegMode(tesserocr.PSM.SPARSE_TEXT)
#
# iterate over all text blocks and compare their
# bbox extent to the running min and max values
for component in tessapi.GetComponentImages(tesserocr.RIL.BLOCK, True):
image, xywh, index, _ = component
#
# the region reference in the reading order element
#
ID = "region%04d" % index
left, top, right, bottom = bbox_from_xywh(xywh)
LOG.debug("Detected text region '%s': %i:%i,%i:%i",
ID, left, right, top, bottom)
# filter region results:
bin_bbox = image.getbbox()
if not bin_bbox:
# this does happen!
LOG.info("Ignoring region '%s' because its binarization is empty", ID)
continue
width = bin_bbox[2]-bin_bbox[0]
if width < 25 / zoom:
# we must be conservative here: page numbers are tiny regions, too!
LOG.info("Ignoring region '%s' because its width is too small (%d)", ID, width)
continue
height = bin_bbox[3]-bin_bbox[1]
if height < 25 / zoom:
# we must be conservative here: page numbers are tiny regions, too!
LOG.debug("Ignoring region '%s' because its height is too small (%d)", ID, height)
continue
all_left = min(all_left, left)
all_top = min(all_top, top)
all_right = max(all_right, right)
all_bottom = max(all_bottom, bottom)
# use existing segmentation as "upper bound"
regions = page.get_AllRegions(classes=['Text'])
for region in regions:
left, top, right, bottom = bbox_from_points(region.get_Coords().points)
LOG.debug("Found existing text region '%s': %i:%i,%i:%i",
region.id, left, right, top, bottom)
all_left = min(all_left, left)
all_top = min(all_top, top)
all_right = max(all_right, right)
all_bottom = max(all_bottom, bottom)
LOG.info("Combined page bounds from text regions: %i:%i,%i:%i",
all_left, all_right, all_top, all_bottom)
return all_left, all_top, all_right, all_bottom
def process(self):
"""Performs page cropping with Tesseract on the workspace.
Open and deserialize PAGE input files and their respective images.
Set up Tesseract to detect text blocks on each page, and find
the largest coordinate extent spanning all of them. Use this
extent in defining a Border, and add that to the page.
Moreover, crop the original image accordingly, and reference the
resulting image file as AlternativeImage in the Page element.
Add the new image file to the workspace along with the output fileGrp,
and using a file ID with suffix ``.IMG-CROP`` along with further
identification of the input element.
Produce new output files by serialising the resulting hierarchy.
"""
LOG = getLogger('processor.TesserocrCrop')
assert_file_grp_cardinality(self.input_file_grp, 1)
assert_file_grp_cardinality(self.output_file_grp, 1)
padding = self.parameter['padding']
with tesserocr.PyTessBaseAPI(path=TESSDATA_PREFIX) as tessapi:
# disable table detection here (tables count as text blocks),
# because we do not want to risk confusing the spine with
# a column separator and thus creeping into a neighbouring
# page:
tessapi.SetVariable("textord_tabfind_find_tables", "0")
for (n, input_file) in enumerate(self.input_files):
page_id = input_file.pageId or input_file.ID
LOG.info("INPUT FILE %i / %s", n, page_id)
pcgts = page_from_file(
self.workspace.download_file(input_file))
self.add_metadata(pcgts)
page = pcgts.get_Page()
# warn of existing Border:
border = page.get_Border()
if border:
left, top, right, bottom = bbox_from_points(
border.get_Coords().points)
LOG.warning('Overwriting existing Border: %i:%i,%i:%i',
left, top, right, bottom)
page_image, page_xywh, page_image_info = self.workspace.image_from_page(
page,
page_id,
# image must not have been cropped already,
# abort if no such image can be produced:
feature_filter='cropped')
if self.parameter['dpi'] > 0:
dpi = self.parameter['dpi']
LOG.info(
"Page '%s' images will use %d DPI from parameter override",
page_id, dpi)
elif page_image_info.resolution != 1:
dpi = page_image_info.resolution
if page_image_info.resolutionUnit == 'cm':
dpi = round(dpi * 2.54)
LOG.info(
"Page '%s' images will use %d DPI from image meta-data",
page_id, dpi)
else:
dpi = 0
LOG.info(
"Page '%s' images will use DPI estimated from segmentation",
page_id)
if dpi:
tessapi.SetVariable('user_defined_dpi', str(dpi))
zoom = 300 / dpi
else:
zoom = 1
# warn of existing segmentation:
regions = page.get_TextRegion()
if regions:
min_x = page_image.width
min_y = page_image.height
max_x = 0
max_y = 0
for region in regions:
left, top, right, bottom = bbox_from_points(
region.get_Coords().points)
min_x = min(min_x, left)
min_y = min(min_y, top)
max_x = max(max_x, right)
max_y = max(max_y, bottom)
LOG.warning(
'Ignoring extent from existing TextRegions: %i:%i,%i:%i',
min_x, max_x, min_y, max_y)
LOG.debug("Cropping with Tesseract")
tessapi.SetImage(page_image)
# PSM.SPARSE_TEXT: get as much text as possible in no particular order
# PSM.AUTO (default): includes tables (dangerous)
tessapi.SetPageSegMode(tesserocr.PSM.SPARSE_TEXT)
#
# helper variables for saving the box coordinates
#
min_x = page_image.width
min_y = page_image.height
max_x = 0
max_y = 0
# iterate over all text blocks and compare their
# bbox extent to the running min and max values
for component in tessapi.GetComponentImages(
tesserocr.RIL.BLOCK, True):
image, xywh, index, _ = component
#
# the region reference in the reading order element
#
ID = "region%04d" % index
left, top, right, bottom = bbox_from_xywh(xywh)
LOG.debug("Detected text region '%s': %i:%i,%i:%i", ID,
left, right, top, bottom)
# filter region results:
bin_bbox = image.getbbox()
if not bin_bbox:
# this does happen!
LOG.info(
"Ignoring region '%s' because its binarization is empty",
ID)
continue
width = bin_bbox[2] - bin_bbox[0]
if width < 25 / zoom:
# we must be conservative here: page numbers are tiny regions, too!
LOG.info(
"Ignoring region '%s' because its width is too small (%d)",
ID, width)
continue
height = bin_bbox[3] - bin_bbox[1]
if height < 25 / zoom:
# we must be conservative here: page numbers are tiny regions, too!
LOG.debug(
"Ignoring region '%s' because its height is too small (%d)",
ID, height)
continue
min_x = min(min_x, left)
min_y = min(min_y, top)
max_x = max(max_x, right)
max_y = max(max_y, bottom)
LOG.info("Updated page border: %i:%i,%i:%i", min_x, max_x,
min_y, max_y)
#
# set the identified page border
#
if min_x < max_x and min_y < max_y:
# add padding:
min_x = max(min_x - padding, 0)
max_x = min(max_x + padding, page_image.width)
min_y = max(min_y - padding, 0)
max_y = min(max_y + padding, page_image.height)
LOG.info("Padded page border: %i:%i,%i:%i", min_x, max_x,
min_y, max_y)
polygon = polygon_from_bbox(min_x, min_y, max_x, max_y)
polygon = coordinates_for_segment(polygon, page_image,
page_xywh)
polygon = polygon_for_parent(polygon, page)
border = BorderType(
Coords=CoordsType(points_from_polygon(polygon)))
# intersection with parent could have changed bbox,
# so recalculate:
bbox = bbox_from_polygon(
coordinates_of_segment(border, page_image, page_xywh))
# update PAGE (annotate border):
page.set_Border(border)
# update METS (add the image file):
page_image = crop_image(page_image, box=bbox)
page_xywh['features'] += ',cropped'
file_id = make_file_id(input_file, self.output_file_grp)
file_path = self.workspace.save_image_file(
page_image,
file_id + '.IMG-CROP',
page_id=input_file.pageId,
file_grp=self.output_file_grp)
# update PAGE (reference the image file):
page.add_AlternativeImage(
AlternativeImageType(filename=file_path,
comments=page_xywh['features']))
else:
LOG.error("Cannot find valid extent for page '%s'",
page_id)
pcgts.set_pcGtsId(file_id)
self.workspace.add_file(ID=file_id,
file_grp=self.output_file_grp,
pageId=input_file.pageId,
mimetype=MIMETYPE_PAGE,
local_filename=os.path.join(
self.output_file_grp,
file_id + '.xml'),
content=to_xml(pcgts))
