315 lines
11 KiB
Python
315 lines
11 KiB
Python
import os
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import copy
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import logging
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import subprocess
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import pyocr
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from PIL import Image
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from .table import Table
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from .imgproc import (adaptive_threshold, find_lines, find_table_contours,
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find_table_joints, find_cuts)
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from .utils import merge_close_values, encode_list
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__all__ = ['OCRLattice', 'OCRStream']
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logger = logging.getLogger('app_logger')
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class OCRLattice:
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"""Lattice, but for images.
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Parameters
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----------
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table_area : list
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List of strings of the form x1,y1,x2,y2 where
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(x1, y1) -> left-top and (x2, y2) -> right-bottom in OpenCV's
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coordinate space, denoting table areas to analyze.
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(optional, default: None)
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mtol : list
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List of ints specifying m-tolerance parameters.
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(optional, default: [2])
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blocksize : int
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Size of a pixel neighborhood that is used to calculate a
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threshold value for the pixel: 3, 5, 7, and so on.
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(optional, default: 15)
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threshold_constant : float
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Constant subtracted from the mean or weighted mean
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(see the details below). Normally, it is positive but may be
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zero or negative as well.
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(optional, default: -2)
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dpi : int
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Dots per inch.
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(optional, default: 300)
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lang : string
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Language to be used for OCR.
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(optional, default: 'eng')
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scale : int
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Used to divide the height/width of a pdf to get a structuring
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element for image processing.
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(optional, default: 15)
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iterations : int
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Number of iterations for dilation.
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(optional, default: 0)
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debug : string
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{'contour', 'line', 'joint', 'table'}
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Set to one of the above values to generate a matplotlib plot
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of detected contours, lines, joints and the table generated.
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(optional, default: None)
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"""
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def __init__(self, table_area=None, mtol=[2], blocksize=15, threshold_constant=-2,
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dpi=300, lang="eng", scale=15, iterations=0, debug=None):
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self.method = 'ocrl'
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self.table_area = table_area
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self.mtol = mtol
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self.blocksize = blocksize
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self.threshold_constant = threshold_constant
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self.tool = pyocr.get_available_tools()[0] # fix this
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self.dpi = dpi
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self.lang = lang
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self.scale = scale
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self.iterations = iterations
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self.debug = debug
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def get_tables(self, pdfname):
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if self.tool is None:
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return None
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bname, __ = os.path.splitext(pdfname)
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imagename = ''.join([bname, '.png'])
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logger.info('Processing {0}.'.format(os.path.basename(bname)))
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gs_call = [
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"-q", "-sDEVICE=png16m", "-o", imagename, "-r{0}".format(self.dpi),
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pdfname
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]
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if "ghostscript" in subprocess.check_output(["gs", "-version"]).lower():
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gs_call.insert(0, "gs")
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else:
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gs_call.insert(0, "gsc")
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subprocess.call(gs_call, stdout=open(os.devnull, 'w'),
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stderr=subprocess.STDOUT)
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img, threshold = adaptive_threshold(imagename, blocksize=self.blocksize,
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c=self.threshold_constant)
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vmask, v_segments = find_lines(threshold, direction='vertical',
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scale=self.scale, iterations=self.iterations)
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hmask, h_segments = find_lines(threshold, direction='horizontal',
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scale=self.scale, iterations=self.iterations)
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if self.table_area is not None:
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areas = []
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for area in self.table_area:
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x1, y1, x2, y2 = area.split(",")
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x1 = int(float(x1))
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y1 = int(float(y1))
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x2 = int(float(x2))
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y2 = int(float(y2))
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areas.append((x1, y1, abs(x2 - x1), abs(y2 - y1)))
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table_bbox = find_table_joints(areas, vmask, hmask)
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else:
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contours = find_table_contours(vmask, hmask)
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table_bbox = find_table_joints(contours, vmask, hmask)
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if self.debug:
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self.debug_images = (img, table_bbox)
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self.debug_segments = (v_segments, h_segments)
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self.debug_tables = []
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if len(self.mtol) == 1 and self.mtol[0] == 2:
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mtolerance = copy.deepcopy(self.mtol) * len(table_bbox)
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else:
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mtolerance = copy.deepcopy(self.mtol)
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page = {}
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tables = {}
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table_no = 0
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for k in sorted(table_bbox.keys(), key=lambda x: x[1]):
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table_data = {}
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cols, rows = zip(*table_bbox[k])
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cols, rows = list(cols), list(rows)
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cols.extend([k[0], k[2]])
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rows.extend([k[1], k[3]])
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cols = merge_close_values(sorted(cols), mtol=mtolerance[table_no])
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rows = merge_close_values(sorted(rows, reverse=True), mtol=mtolerance[table_no])
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cols = [(cols[i], cols[i + 1])
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for i in range(0, len(cols) - 1)]
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rows = [(rows[i], rows[i + 1])
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for i in range(0, len(rows) - 1)]
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table = Table(cols, rows)
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if self.debug:
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self.debug_tables.append(table)
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table.image = img[k[3]:k[1],k[0]:k[2]]
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for i in range(len(table.cells)):
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for j in range(len(table.cells[i])):
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x1 = int(table.cells[i][j].x1)
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y1 = int(table.cells[i][j].y1)
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x2 = int(table.cells[i][j].x2)
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y2 = int(table.cells[i][j].y2)
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table.cells[i][j].image = img[y1:y2,x1:x2]
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text = self.tool.image_to_string(
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Image.fromarray(table.cells[i][j].image),
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lang=self.lang,
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builder=pyocr.builders.TextBuilder()
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)
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table.cells[i][j].add_text(text)
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ar = table.get_list()
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ar.reverse()
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ar = encode_list(ar)
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table_data['data'] = ar
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tables['table-{0}'.format(table_no + 1)] = table_data
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table_no += 1
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page[os.path.basename(bname)] = tables
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if self.debug:
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return None
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return page
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class OCRStream:
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"""Stream, but for images.
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Parameters
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----------
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table_area : list
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List of strings of the form x1,y1,x2,y2 where
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(x1, y1) -> left-top and (x2, y2) -> right-bottom in OpenCV's
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coordinate space, denoting table areas to analyze.
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(optional, default: None)
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columns : list
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List of strings where each string is comma-separated values of
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x-coordinates in OpenCV's coordinate space.
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(optional, default: None)
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blocksize : int
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Size of a pixel neighborhood that is used to calculate a
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threshold value for the pixel: 3, 5, 7, and so on.
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(optional, default: 15)
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threshold_constant : float
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Constant subtracted from the mean or weighted mean
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(see the details below). Normally, it is positive but may be
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zero or negative as well.
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(optional, default: -2)
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line_threshold : int
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Maximum intensity of projections on y-axis.
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(optional, default: 100)
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dpi : int
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Dots per inch.
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(optional, default: 300)
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lang : string
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Language to be used for OCR.
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(optional, default: 'eng')
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"""
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def __init__(self, table_area=None, columns=None, blocksize=15,
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threshold_constant=-2, line_threshold=100, dpi=300, lang="eng",
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debug=False):
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self.method = 'ocrs'
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self.table_area = table_area
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self.columns = columns
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self.blocksize = blocksize
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self.threshold_constant = threshold_constant
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self.line_threshold = line_threshold
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self.tool = pyocr.get_available_tools()[0] # fix this
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self.dpi = dpi
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self.lang = lang
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self.debug = debug
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def get_tables(self, pdfname):
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if self.tool is None:
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return None
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bname, __ = os.path.splitext(pdfname)
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imagename = ''.join([bname, '.png'])
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logger.info('Processing {0}.'.format(os.path.basename(bname)))
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gs_call = [
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"-q", "-sDEVICE=png16m", "-o", imagename, "-r{0}".format(self.dpi),
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pdfname
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]
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if "ghostscript" in subprocess.check_output(["gs", "-version"]).lower():
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gs_call.insert(0, "gs")
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else:
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gs_call.insert(0, "gsc")
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subprocess.call(gs_call, stdout=open(os.devnull, 'w'),
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stderr=subprocess.STDOUT)
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img, threshold = adaptive_threshold(imagename, blocksize=self.blocksize,
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c=self.threshold_constant)
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height, width = threshold.shape
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if self.debug:
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self.debug_images = img
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return None
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if self.table_area is not None:
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if self.columns is not None:
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if len(self.table_area) != len(self.columns):
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raise ValueError("{0}: Length of table area and columns"
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" should be equal.".format(os.path.basename(bname)))
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table_bbox = {}
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for area in self.table_area:
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x1, y1, x2, y2 = area.split(",")
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x1 = int(float(x1))
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y1 = int(float(y1))
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x2 = int(float(x2))
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y2 = int(float(y2))
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table_bbox[(x1, y1, x2, y2)] = None
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else:
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table_bbox = {(0, 0, width, height): None}
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page = {}
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tables = {}
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table_no = 0
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for k in sorted(table_bbox.keys(), key=lambda x: x[1]):
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if self.columns is None:
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raise NotImplementedError
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else:
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table_data = {}
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table_image = threshold[k[1]:k[3],k[0]:k[2]]
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cols = self.columns[table_no].split(',')
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cols = [float(c) for c in cols]
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cols.insert(0, k[0])
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cols.append(k[2])
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cols = [(cols[i] - k[0], cols[i + 1] - k[0]) for i in range(0, len(cols) - 1)]
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y_cuts = find_cuts(table_image, line_threshold=self.line_threshold)
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rows = [(y_cuts[i], y_cuts[i + 1]) for i in range(0, len(y_cuts) - 1)]
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table = Table(cols, rows)
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for i in range(len(table.cells)):
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for j in range(len(table.cells[i])):
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x1 = int(table.cells[i][j].x1)
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y1 = int(table.cells[i][j].y1)
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x2 = int(table.cells[i][j].x2)
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y2 = int(table.cells[i][j].y2)
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table.cells[i][j].image = table_image[y1:y2,x1:x2]
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cell_image = Image.fromarray(table.cells[i][j].image)
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text = self.tool.image_to_string(
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cell_image,
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lang=self.lang,
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builder=pyocr.builders.TextBuilder()
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)
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table.cells[i][j].add_text(text)
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ar = table.get_list()
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ar.reverse()
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ar = encode_list(ar)
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table_data['data'] = ar
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tables['table-{0}'.format(table_no + 1)] = table_data
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table_no += 1
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page[os.path.basename(bname)] = tables
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return page |