54 lines
1.8 KiB
Python
54 lines
1.8 KiB
Python
from functools import partial
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import cv2
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import numpy as np
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import pdf2image
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from iteration_utilities import starfilter, first
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from cv_analysis.utils.display import show_mpl
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from cv_analysis.utils.draw import draw_contours
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from cv_analysis.utils.filters import is_large_enough, is_filled, is_boxy
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from cv_analysis.utils.visual_logging import vizlogger
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def is_likely_redaction(contour, hierarchy, min_area):
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return is_filled(hierarchy) and is_boxy(contour) and is_large_enough(contour, min_area)
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def find_redactions(image: np.array, min_normalized_area=200000):
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vizlogger.debug(image, "redactions01_start.png")
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min_normalized_area /= 200 # Assumes 200 DPI PDF -> image conversion resolution
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if len(image.shape) > 2:
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gray = ~cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
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else:
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gray = ~image
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vizlogger.debug(gray, "redactions02_gray.png")
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blurred = cv2.GaussianBlur(gray, (5, 5), 1)
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vizlogger.debug(blurred, "redactions03_blur.png")
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thresh = cv2.threshold(blurred, 252, 255, cv2.THRESH_BINARY)[1]
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vizlogger.debug(blurred, "redactions04_threshold.png")
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contours, hierarchies = cv2.findContours(thresh, cv2.RETR_TREE, cv2.CHAIN_APPROX_NONE)
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try:
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contours = map(
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first, starfilter(partial(is_likely_redaction, min_area=min_normalized_area), zip(contours, hierarchies[0]))
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)
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return list(contours)
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except:
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return []
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def annotate_redactions_in_pdf(pdf_path, page_index=1, show=False):
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page = pdf2image.convert_from_path(pdf_path, first_page=page_index + 1, last_page=page_index + 1)[0]
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page = np.array(page)
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redaction_contours = find_redactions(page)
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page = draw_contours(page, redaction_contours)
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vizlogger.debug(page, "redactions05_output.png")
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if show:
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show_mpl(page)
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