org.apache.tika.parser.ocr.rotation.py Maven / Gradle / Ivy
"""
Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements. See the NOTICE file distributed with
this work for additional information regarding copyright ownership.
The ASF licenses this file to You under the Apache License, Version 2.0
(the "License"); you may not use this file except in compliance with
the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
"""
from __future__ import division, print_function
import numpy
from skimage.transform import radon
from PIL import Image
from numpy import asarray, mean, array, blackman
from numpy.fft import rfft
import matplotlib.pyplot as plt
from matplotlib.mlab import rms_flat
import sys
import getopt
def main(argv):
filename = ''
if len(sys.argv) < 3:
print('Usage: rotation.py -f ')
sys.exit()
try:
opts, args = getopt.getopt(argv,"hf:",["file="])
except getopt.GetoptError:
print('rotation.py -f ')
sys.exit(2)
for opt, arg in opts:
if opt == '-h':
print('Usage: rotation.py -f ')
sys.exit()
elif opt in ("-f", "--file"):
filename = arg
try:
from parabolic import parabolic
def argmax(x):
return parabolic(x, numpy.argmax(x))[0]
except ImportError:
from numpy import argmax
# Load file, converting to grayscale
I = asarray(Image.open(filename).convert('L'))
I = I - mean(I) # Demean; make the brightness extend above and below zero
# Do the radon transform and display the result
sinogram = radon(I)
# Find the RMS value of each row and find "busiest" rotation,
# where the transform is lined up perfectly with the alternating dark
# text and white lines
r = array([rms_flat(line) for line in sinogram.transpose()])
rotation = argmax(r)
print('{:.2f}'.format(-(90-rotation)))
if __name__ == "__main__":
main(sys.argv[1:])