Coverage for /Users/virantha/dev/ocr/pypdfocr/pypdfocr_preprocess : 83%

#!/usr/bin/env python2.7 

# Copyright 2013 Virantha Ekanayake All Rights Reserved. 

# 

# Licensed 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. 

""" 

    Wrap ImageMagick calls.  Yes, this is ugly. 

""" 

import subprocess 

import sys, os 

import logging 

import glob 

import functools 

import signal 

from multiprocessing import Pool 

from pypdfocr_interrupts import init_worker 

# Ugly hack to pass in object method to the multiprocessing library 

# From http://www.rueckstiess.net/research/snippets/show/ca1d7d90 

# Basically gets passed in a pair of (self, arg), and calls the method 

def unwrap_self(arg, **kwarg): 

    return PyPreprocess._run_preprocess(*arg, **kwarg) 

class PyPreprocess(object): 

    """Class to wrap all the ImageMagick convert calls""" 

    def __init__(self, config): 

        self.msgs = { 

                'CV_FAILED': 'convert execution failed', 

            } 

        self.threads = config.get('threads', 4) 

    def _warn(self, msg): # pragma: no cover 

        print("WARNING: %s" % msg) 

    def cmd(self, cmd_list): 

        if isinstance(cmd_list, list): 

            cmd_list = ' '.join(cmd_list) 

        logging.debug("Running cmd: %s" % cmd_list) 

        try: 

            out = subprocess.check_output(cmd_list, stderr=subprocess.STDOUT, shell=True) 

            logging.debug(out) 

            return out 

        except subprocess.CalledProcessError as e: 

            print e.output 

            self._warn("Could not run command %s" % cmd_list) 

    def _run_preprocess(self,  in_filename): 

        basename, filext = os.path.splitext(in_filename) 

        out_filename = '%s_preprocess%s' % (basename, filext) 

        #-respect-parenthesis \( -clone 0 -colorspace gray -negate -lat 15x5+5% -contrast-stretch 0 \) -compose copy_opacity -composite -opaque none +matte -modulate 100,50 -adaptive-blur 2.0 -sharpen 0x1  

        # When using Windows, can't use backslash parenthesis in the shell, so omit the backslash 

        if str(os.name) == 'nt': 

            backslash = '' 

        else: 

            backslash = '\\' 

        c = ['convert', 

                '"%s"' % in_filename, 

                '-respect-parenthesis', 

                #'\\( $setcspace -colorspace gray -type grayscale \\)', 

                backslash+'(', 

                '-clone 0', 

                '-colorspace gray -negate -lat 15x15+5% -contrast-stretch 0', 

                backslash+') -compose copy_opacity -composite -opaque none +matte -modulate 100,100', 

                #'-adaptive-blur 1.0', 

                '-blur 1x1', 

                #'-selective-blur 4x4+5%', 

                '-adaptive-sharpen 0x2', 

                '-negate -define morphology:compose=darken -morphology Thinning Rectangle:1x30+0+0 -negate ',  # Removes vertical lines >=60 pixes, reduces widht of >30 (oherwise tesseract < 3.03 completely ignores text close to vertical lines in a table) 

                '"%s"' % (out_filename) 

                ] 

        logging.info("Preprocessing image %s for better OCR" % in_filename) 

        res = self.cmd(c) 

        if res is None: 

            return in_filename 

        else: 

            return out_filename 

    def preprocess(self, in_filenames): 

        fns = in_filenames 

        pool = Pool(processes=self.threads, initializer=init_worker) 

        try: 

            logging.info("Starting preprocessing parallel execution") 

            preprocessed_filenames = pool.map(unwrap_self,zip([self]*len(fns),fns)) 

            pool.close() 

        except KeyboardInterrupt or Exception: 

            print("Caught keyboard interrupt... terminating") 

            pool.terminate() 

            #sys,exit(-1) 

            raise 

        finally: 

            pool.join() 

            logging.info ("Completed preprocessing") 

        return preprocessed_filenames