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Parameterize thresholding blocksize and constant

pull/2/head
Vinayak Mehta 2017-04-10 21:15:54 +05:30
parent 8b07aa2702
commit 72233f25ce
5 changed files with 143 additions and 61 deletions
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22
camelot/lattice.py
View File

@ -139,6 +139,17 @@ class Lattice:
List of ints specifying m-tolerance parameters.
(optional, default: [2])
blocksize: int
Size of a pixel neighborhood that is used to calculate a
threshold value for the pixel: 3, 5, 7, and so on.
(optional, default: 15)
threshold_constant: float
Constant subtracted from the mean or weighted mean
(see the details below). Normally, it is positive but may be
zero or negative as well.
(optional, default: -2)
scale : int
Used to divide the height/width of a pdf to get a structuring
element for image processing.
@ -177,15 +188,17 @@ class Lattice:
(optional, default: None)
"""
def __init__(self, table_area=None, fill=None, headers=None, mtol=[2],
scale=15, invert=False, margins=(1.0, 0.5, 0.1),
split_text=False, flag_size=True, shift_text=['l', 't'],
debug=None):
blocksize=15, threshold_constant=-2, scale=15, invert=False,
margins=(1.0, 0.5, 0.1), split_text=False, flag_size=True,
shift_text=['l', 't'], debug=None):
self.method = 'lattice'
self.table_area = table_area
self.fill = fill
self.headers = headers
self.mtol = mtol
self.blocksize = blocksize
self.threshold_constant = threshold_constant
self.scale = scale
self.invert = invert
self.char_margin, self.line_margin, self.word_margin = margins
@ -230,7 +243,8 @@ class Lattice:
subprocess.call(gs_call, stdout=open(os.devnull, 'w'),
stderr=subprocess.STDOUT)
img, threshold = adaptive_threshold(imagename, invert=self.invert)
img, threshold = adaptive_threshold(imagename, invert=self.invert,
blocksize=self.blocksize, c=self.threshold_constant)
pdf_x = width
pdf_y = height
img_x = img.shape[1]

20
camelot/ocr.py
View File

@ -27,6 +27,17 @@ class OCR:
List of ints specifying m-tolerance parameters.
(optional, default: [2])
blocksize: int
Size of a pixel neighborhood that is used to calculate a
threshold value for the pixel: 3, 5, 7, and so on.
(optional, default: 15)
threshold_constant: float
Constant subtracted from the mean or weighted mean
(see the details below). Normally, it is positive but may be
zero or negative as well.
(optional, default: -2)
dpi : int
Dots per inch.
(optional, default: 300)
@ -46,12 +57,14 @@ class OCR:
of detected contours, lines, joints and the table generated.
(optional, default: None)
"""
def __init__(self, table_area=None, mtol=[2], dpi=300, lang="eng", scale=15,
debug=None):
def __init__(self, table_area=None, mtol=[2], blocksize=15, threshold_constant=-2,
dpi=300, lang="eng", scale=15, debug=None):
self.method = 'ocr'
self.table_area = table_area
self.mtol = mtol
self.blocksize = blocksize
self.threshold_constant = threshold_constant
self.tool = pyocr.get_available_tools()[0] # fix this
self.dpi = dpi
self.lang = lang
@ -75,7 +88,8 @@ class OCR:
subprocess.call(gs_call, stdout=open(os.devnull, 'w'),
stderr=subprocess.STDOUT)
img, threshold = adaptive_threshold(imagename)
img, threshold = adaptive_threshold(imagename, blocksize=self.blocksize,
c=self.threshold_constant)
vmask, v_segments = find_lines(threshold, direction='vertical',
scale=self.scale)
hmask, h_segments = find_lines(threshold, direction='horizontal',

3
camelot/utils.py
View File

@ -570,6 +570,7 @@ def get_score(error_weights):
score : float
"""
SCORE_VAL = 100
try:
score = 0
if sum([ew[0] for ew in error_weights]) != SCORE_VAL:
raise ValueError("Please assign a valid weightage to each parameter"
@ -578,6 +579,8 @@ def get_score(error_weights):
weight = ew[0] / len(ew[1])
for error_percentage in ew[1]:
score += weight * (1 - error_percentage)
except ZeroDivisionError:
score = 0
return score

41
debug/threshold.py 100644
View File

@ -0,0 +1,41 @@
"""
usage: python threshold.py file.png blocksize threshold_constant
shows thresholded image.
"""
import sys
import time
import cv2
import numpy as np
import matplotlib.pyplot as plt
def timeit(func):
def timed(*args, **kw):
start = time.time()
result = func(*args, **kw)
end = time.time()
print 'Function: %r took: %2.4f seconds' % (func.__name__, end - start)
return result
return timed
@timeit
def main():
img = cv2.imread(sys.argv[1])
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
blocksize = int(sys.argv[2])
threshold_constant = float(sys.argv[3])
threshold = cv2.adaptiveThreshold(np.invert(gray), 255,
cv2.ADAPTIVE_THRESH_GAUSSIAN_C, cv2.THRESH_BINARY, blocksize, threshold_constant)
plt.imshow(img)
plt.show()
if __name__ == '__main__':
if len(sys.argv) == 1:
print __doc__
else:
main()

82
tools/camelot
View File

@ -71,6 +71,8 @@ options:
-H, --header <header> Specify header for each table.
-m, --mtol <mtol> Tolerance to account for when merging lines
which are very close. [default: 2]
-b, --blocksize <blocksize> See adaptive threshold doc. [default: 15]
-c, --constant <constant> See adaptive threshold doc. [default: -2]
-s, --scale <scale> Scaling factor. Large scaling factor leads to
smaller lines being detected. [default: 15]
-i, --invert Invert pdf image to make sure that lines are
@ -112,6 +114,8 @@ options:
-t, --tarea <tarea> Specific table areas to analyze.
-m, --mtol <mtol> Tolerance to account for when merging lines
which are very close. [default: 2]
-b, --blocksize <blocksize> See adaptive threshold doc. [default: 15]
-c, --constant <constant> See adaptive threshold doc. [default: -2]
-D, --dpi <dpi> Dots per inch, specify image quality to be used for OCR.
[default: 300]
-l, --lang <lang> Specify language to be used for OCR. [default: eng]
@ -374,20 +378,23 @@ if __name__ == '__main__':
float(args['--wmargin']))
if args['<method>'] == 'lattice':
try:
tarea = args['--tarea'] if args['--tarea'] else None
fill = args['--fill'] if args['--fill'] else None
header = args['--header'] if args['--header'] else None
mtol = [int(m) for m in args['--mtol']]
shift_text = list(args['--shift_text']) if args['--shift_text'] else ['l', 't']
manager = Pdf(Lattice(table_area=tarea, fill=fill, headers=header,
mtol=mtol, scale=int(args['--scale']),
invert=args['--invert'], margins=margins,
split_text=args['--split_text'], flag_size=args['--flag_size'],
shift_text=shift_text, debug=args['--debug']),
filename,
pagenos=p,
parallel=args['--parallel'],
clean=True)
kwargs = {
'table_area': args['--tarea'] if args['--tarea'] else None,
'fill': args['--fill'] if args['--fill'] else None,
'headers': args['--header'] if args['--header'] else None,
'mtol': [int(m) for m in args['--mtol']],
'blocksize': int(args['--blocksize']),
'threshold_constant': float(args['--constant']),
'scale': int(args['--scale']),
'invert': args['--invert'],
'margins': margins,
'split_text': args['--split_text'],
'flag_size': args['--flag_size'],
'shift_text': list(args['--shift_text']) if args['--shift_text'] else ['l', 't'],
'debug': args['--debug']
}
manager = Pdf(Lattice(**kwargs), filename, pagenos=p, clean=True,
parallel=args['--parallel'])
data = manager.extract()
processing_time = time.time() - start_time
@ -441,19 +448,19 @@ if __name__ == '__main__':
sys.exit()
elif args['<method>'] == 'stream':
try:
tarea = args['--tarea'] if args['--tarea'] else None
columns = args['--columns'] if args['--columns'] else None
header = args['--header'] if args['--header'] else None
ytol = [int(y) for y in args['--ytol']]
mtol = [int(m) for m in args['--mtol']]
manager = Pdf(Stream(table_area=tarea, columns=columns,
headers=header, ytol=ytol, mtol=mtol,
margins=margins, split_text=args['--split_text'],
flag_size=args['--flag_size'], debug=args['--debug']),
filename,
pagenos=p,
parallel=args['--parallel'],
clean=True)
kwargs = {
'table_area': args['--tarea'] if args['--tarea'] else None,
'columns': args['--columns'] if args['--columns'] else None,
'headers': args['--header'] if args['--header'] else None,
'ytol': [int(y) for y in args['--ytol']],
'mtol': [int(m) for m in args['--mtol']],
'margins': margins,
'split_text': args['--split_text'],
'flag_size': args['--flag_size'],
'debug': args['--debug']
}
manager = Pdf(Stream(**kwargs), filename, pagenos=p, clean=True,
parallel=args['--parallel'])
data = manager.extract()
processing_time = time.time() - start_time
@ -506,15 +513,18 @@ if __name__ == '__main__':
sys.exit()
elif args['<method>'] == 'ocr':
try:
tarea = args['--tarea'] if args['--tarea'] else None
mtol = [int(m) for m in args['--mtol']]
manager = Pdf(OCR(table_area=tarea, mtol=mtol, dpi=int(args['--dpi']),
lang=args['--lang'], scale=int(args['--scale']),
debug=args['--debug']),
filename,
pagenos=p,
parallel=args['--parallel'],
clean=True)
kwargs = {
'table_area': args['--tarea'] if args['--tarea'] else None,
'mtol': [int(m) for m in args['--mtol']],
'blocksize': int(args['--blocksize']),
'threshold_constant': float(args['--constant']),
'dpi': int(args['--dpi']),
'lang': args['--lang'],
'scale': int(args['--scale']),
'debug': args['--debug']
}
manager = Pdf(OCR(**kwargs), filename, pagenos=p, clean=True,
parallel=args['--parallel'])
data = manager.extract()
processing_time = time.time() - start_time