Code to remove lines from sheet music files and/or display them

HoughLines.py

__author__ = 'asanyal'

import cv2
import numpy as np

def getHoughLines(imgFile):
    img = cv2.imread(imgFile)
    gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
    edges = cv2.Canny(gray,50,150,apertureSize = 3)

    lines = cv2.HoughLines(edges, 1, np.pi/180, 200)

    for line in lines:
        for rho,theta in line:
            a = np.cos(theta)
            b = np.sin(theta)
            x0 = a*rho
            y0 = b*rho
            x1 = int(x0 + 1000*(-b))
            y1 = int(y0 + 1000*(a))
            x2 = int(x0 - 1000*(-b))
            y2 = int(y0 - 1000*(a))

            cv2.line(img,(x1,y1),(x2,y2),(0,0,255),2)

    cv2.imshow('gray',img)
    cv2.waitKey(0)

def removeLinesFromSheet(imgFile):

    img = cv2.imread(imgFile)

    gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
    adaptiveThreshHoldImage = cv2.adaptiveThreshold(~gray, 255, cv2.ADAPTIVE_THRESH_MEAN_C, cv2.THRESH_BINARY, 15, -2)

    cv2.imshow('gray', adaptiveThreshHoldImage)

    horizontal = adaptiveThreshHoldImage.copy()
    vertical = adaptiveThreshHoldImage.copy()

    (rows, cols) = adaptiveThreshHoldImage.shape

    horizontalSize = cols/30
    verticalSize = rows/30

    horizontalStructure = cv2.getStructuringElement(cv2.MORPH_RECT,(horizontalSize, 1))

    horizontal = cv2.erode(horizontal, horizontalStructure, iterations = 1)
    horizontal = cv2.dilate(horizontal, horizontalStructure, iterations = 1)

    cv2.imshow('horizontal', horizontal)

    verticalStructure = cv2.getStructuringElement(cv2.MORPH_RECT,(1, 3))

    vertical = cv2.erode(vertical, verticalStructure, iterations = 1);
    vertical = cv2.dilate(vertical, verticalStructure, iterations = 1);

    vertical = cv2.bitwise_not(vertical)

    cv2.imshow('vertical', vertical)

    smoothedThreshHoldImg = cv2.adaptiveThreshold(vertical, 255, cv2.ADAPTIVE_THRESH_MEAN_C, cv2.THRESH_BINARY, 3, -2)

    cv2.imshow('edges', smoothedThreshHoldImg)

    cv2.waitKey(0)

def read_staff_lines(img):
	edges = cv2.Canny(img,150,700)

	lines = cv2.HoughLines(edges,1,np.pi/180,200)
	staff_lines = []
	for rho,theta in lines[0]:
	    a = np.cos(theta)
	    b = np.sin(theta)
	    x0 = a*rho
	    y0 = b*rho
	    x1 = int(x0 + 1000*(-b))
	    y1 = int(y0 + 1000*(a))
	    x2 = int(x0 - 1000*(-b))
	    y2 = int(y0 - 1000*(a))

	    th = 10 #pixels
	    too_close = False

	    # only appends lines if they're a reasonable distance
	    # from other lines
	    # would be better if used averaging between close lines instead of
	    # just taking the first one we see and tossing the other
	    for y in staff_lines:
	      	if abs(y - y1) <= th:
	    		too_close = True
	    if not too_close:
	    	staff_lines.append((y1))

	return staff_lines

# Running a test case
def main():
    getHoughLines("sampleFile.png")
    removeLinesFromSheet("sampleFile.png")

main()