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sbb_textline_detection
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ensure valid coordinates by intersection with parent…

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- Border: intersect with page frame
- text regions: intersect with (new) Border
- text lines: intersect with (new) text region
  (and back-transform at all)
pull/48/head
Robert Sachunsky 4 years ago
parent 247d5f9fc2
commit 261db14ec3
2 changed files with 112 additions and 41 deletions
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150
qurator/sbb_textline_detector/ocrd_cli.py
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@ -7,17 +7,17 @@ import ocrd_models.ocrd_page
from ocrd import Processor
from ocrd.decorators import ocrd_cli_options, ocrd_cli_wrap_processor
from ocrd_modelfactory import page_from_file
from ocrd_models import OcrdFile
from ocrd_models.ocrd_page_generateds import MetadataItemType, LabelsType, LabelType, \
CoordsType
from ocrd_models.ocrd_page_generateds import CoordsType, PageType
from ocrd_utils import (
assert_file_grp_cardinality,
getLogger,
make_file_id,
MIMETYPE_PAGE,
coordinates_for_segment,
polygon_from_points, points_from_polygon,
)
import numpy as np
from shapely.geometry import Polygon, asPolygon
from shapely.ops import unary_union
from pkg_resources import resource_string
@ -63,8 +63,8 @@ class OcrdSbbTextlineDetectorRecognize(Processor):
page = pcgts.get_Page()
page_image, page_coords, page_image_info = \
self.workspace.image_from_page(
page, page_id,
feature_filter='cropped,binarized,grayscale_normalized'
page, page_id,
feature_filter='cropped,binarized,grayscale_normalized'
)
with tempfile.TemporaryDirectory() as tmp_dirname:
@ -84,64 +84,134 @@ class OcrdSbbTextlineDetectorRecognize(Processor):
# Create a new PAGE file from the input file
pcgts.set_pcGtsId(file_id)
page = pcgts.get_Page()
# Merge results → PAGE file
# 1. Border
if page.get_Border():
log.warning("Page already contained a border")
log.warning("Removing existing page border")
page.set_Border(None)
# We need to translate the coordinates:
text_border = tmp_page.get_Border()
coords = text_border.get_Coords().get_points()
polygon = polygon_from_points(coords)
polygon_new = coordinates_for_segment(polygon, page_image, page_coords)
points_new = points_from_polygon(polygon_new)
coords_new = CoordsType(points=points_new)
text_border.set_Coords(coords_new)
page.set_Border(text_border)
text_border = adapt_coords(tmp_page.get_Border(), page, page_coords)
if text_border is None:
# intersection is empty (border outside of rotated original image)
log.warning("new border would be empty, skipping")
else:
page.set_Border(text_border)
# 2. ReadingOrder
if page.get_ReadingOrder():
log.warning("Page already contained a reading order")
log.warning("Removing existing regions' reading order")
page.set_ReadingOrder(tmp_page.get_ReadingOrder())
# 3. TextRegion
# FIXME: what about table and image regions?
if page.get_TextRegion():
log.warning("Page already contained text regions")
log.warning("Removing existing text regions")
# We need to translate the coordinates:
text_regions_new = []
for text_region in tmp_page.get_TextRegion():
coords = text_region.get_Coords().get_points()
polygon = polygon_from_points(coords)
polygon_new = coordinates_for_segment(polygon, page_image, page_coords)
points_new = points_from_polygon(polygon_new)
coords_new = CoordsType(points=points_new)
text_region.set_Coords(coords_new)
text_region = adapt_coords(text_region, page, page_coords)
if text_region is None:
# intersection is empty (polygon outside of above border)
log.warning("new text region polygon would be empty, skipping")
continue
text_regions_new.append(text_region)
text_lines_new = []
for text_line in text_region.get_TextLine():
text_line = adapt_coords(text_line, text_region, page_coords)
if text_line is None:
# intersection is empty (polygon outside of region)
log.warning("new text line polygon would be empty, skipping")
continue
text_lines_new.append(text_line)
text_region.set_TextLine(text_lines_new)
page.set_TextRegion(text_regions_new)
# Save metadata about this operation
metadata = pcgts.get_Metadata()
metadata.add_MetadataItem(
MetadataItemType(type_="processingStep",
name=self.ocrd_tool['steps'][0],
value=TOOL,
Labels=[LabelsType(
externalModel="ocrd-tool",
externalId="parameters",
Label=[LabelType(type_=name, value=self.parameter[name])
for name in self.parameter.keys()])]))
self.add_metadata(pcgts)
self.workspace.add_file(
ID=file_id,
file_grp=self.output_file_grp,
pageId=page_id,
mimetype='application/vnd.prima.page+xml',
local_filename=os.path.join(self.output_file_grp, file_id) + '.xml',
content=ocrd_models.ocrd_page.to_xml(pcgts)
ID=file_id,
file_grp=self.output_file_grp,
pageId=page_id,
mimetype='application/vnd.prima.page+xml',
local_filename=os.path.join(self.output_file_grp, file_id) + '.xml',
content=ocrd_models.ocrd_page.to_xml(pcgts)
)
def adapt_coords(segment, parent, transform):
points = segment.get_Coords().get_points()
polygon = polygon_from_points(points)
# polygon absolute coords (after transforming back from page coords, e.g. deskewing)
polygon_new = coordinates_for_segment(polygon, None, transform)
# intersection with parent polygon
polygon_new = polygon_for_parent(polygon_new, parent)
if polygon_new is None:
return None
points_new = points_from_polygon(polygon_new)
segment.set_Coords(CoordsType(points=points_new))
return segment
# from ocrd_tesserocr, to be integrated into core (somehow)...
def polygon_for_parent(polygon, parent):
"""Clip polygon to parent polygon range.
(Should be moved to ocrd_utils.coordinates_for_segment.)
"""
childp = Polygon(polygon)
if isinstance(parent, PageType):
if parent.get_Border():
parentp = Polygon(polygon_from_points(parent.get_Border().get_Coords().points))
else:
parentp = Polygon([[0, 0], [0, parent.get_imageHeight()],
[parent.get_imageWidth(), parent.get_imageHeight()],
[parent.get_imageWidth(), 0]])
else:
parentp = Polygon(polygon_from_points(parent.get_Coords().points))
# check if clipping is necessary
if childp.within(parentp):
return polygon
# ensure input coords have valid paths (without self-intersection)
# (this can happen when shapes valid in floating point are rounded)
childp = make_valid(childp)
parentp = make_valid(parentp)
# clip to parent
interp = childp.intersection(parentp)
if interp.is_empty or interp.area == 0.0:
# this happens if Tesseract "finds" something
# outside of the valid Border of a deskewed/cropped page
# (empty corners created by masking); will be ignored
return None
if interp.type == 'GeometryCollection':
# heterogeneous result: filter zero-area shapes (LineString, Point)
interp = unary_union([geom for geom in interp.geoms if geom.area > 0])
if interp.type == 'MultiPolygon':
# homogeneous result: construct convex hull to connect
# FIXME: construct concave hull / alpha shape
interp = interp.convex_hull
if interp.minimum_clearance < 1.0:
# follow-up calculations will necessarily be integer;
# so anticipate rounding here and then ensure validity
interp = asPolygon(np.round(interp.exterior.coords))
interp = make_valid(interp)
return interp.exterior.coords[:-1] # keep open
# from ocrd_tesserocr, to be integrated into core (somehow)...
def make_valid(polygon):
for split in range(1, len(polygon.exterior.coords)-1):
if polygon.is_valid or polygon.simplify(polygon.area).is_valid:
break
# simplification may not be possible (at all) due to ordering
# in that case, try another starting point
polygon = Polygon(polygon.exterior.coords[-split:]+polygon.exterior.coords[:-split])
for tolerance in range(1, int(polygon.area)):
if polygon.is_valid:
break
# simplification may require a larger tolerance
polygon = polygon.simplify(tolerance)
return polygon
if __name__ == '__main__':
ocrd_sbb_textline_detector()

3
requirements.txt
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@ -8,4 +8,5 @@ scikit-learn
numpy == 1.18.* # XXX for tensorflow-gpu 1.15
tensorflow-gpu ~=1.15.2
scipy
ocrd >= 2.0.0
ocrd >= 2.18.0
shapely >= 1.7.1

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