functions_lines.py

import cv2
import numpy as np

def findLines(bw_image, LinesThres):
	# making horizontal projections
	
	horProj = cv2.reduce(bw_image, 1, cv2.cv.CV_REDUCE_AVG)

	# make hist - same dimension as horProj - if 0 (space), then True, else False
	th = 0; # black pixels threshold value. this represents the space lines
	hist = horProj <= th;

	#Get mean coordinate of white white pixels groups
	ycoords = []
	y = 0
	count = 0
	isSpace = False

	for i in range(0, bw_image.shape[0]):
		
		if (not isSpace):
			if (hist[i]): #if space is detected, get the first starting y-coordinates and start count at 1
				isSpace = True
				count = 1
				y = i
		else:
			if (not hist[i]):
				isSpace = False
				#when smoothing, thin letters will breakdown, creating a new blank lines or pixel rows, but the count will be small, so we set a threshold.
				if (count >=LinesThres):
					ycoords.append(y / count)
			else:
				y = y + i
				count = count + 1

	ycoords.append(y / count)
	
	#returns y-coordinates of the lines found
	return ycoords

def LinesMedian(bw_image):
	# making horizontal projections
	
	horProj = cv2.reduce(bw_image, 1, cv2.cv.CV_REDUCE_AVG)

	# make hist - same dimension as horProj - if 0 (space), then True, else False
	th = 0; # black pixels threshold value. this represents the space lines
	hist = horProj <= th;

	#Get mean coordinate of white white pixels groups
	ycoords = []
	y = 0
	count = 0
	isSpace = False
	median_count = []

	for i in range(0, bw_image.shape[0]):
		
		if (not isSpace):
			if (hist[i]): #if space is detected, get the first starting y-coordinates and start count at 1
				isSpace = True
				count = 1
				#y = i
		else:
			if (not hist[i]):
				isSpace = False
				median_count.append(count)
			else:
				#y = y + i
				count = count + 1
	median_count.append(count)
	#ycoords.append(y / count)
	
	#returns counts of each blank rows of each of the lines found
	return median_count

def get_lines_threshold(percent, img_for_det):
	ThresPercent = percent
	LinMed = LinesMedian(img_for_det)
	LinMed = sorted(LinMed)
	LinesThres = LinMed[len(LinMed)/3]*(ThresPercent/100.0)
	LinesThres = int(LinesThres)
	return LinesThres