Python/digital_image_processing/histogram_equalization/histogram_stretch.py

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# -*- coding: utf-8 -*-
"""
Created on Fri Sep 28 15:22:29 2018
@author: Binish125
"""
import copy
import os
import numpy as np
import cv2
import matplotlib.pyplot as plt
class contrastStretch:
def __init__(self):
self.img = ""
self.original_image = ""
self.last_list = []
self.rem = 0
self.L = 256
self.sk = 0
self.k = 0
self.number_of_rows = 0
self.number_of_cols = 0
def stretch(self, input_image):
self.img = cv2.imread(input_image, 0)
self.original_image = copy.deepcopy(self.img)
x, _, _ = plt.hist(self.img.ravel(), 256, [0, 256], label="x")
self.k = np.sum(x)
for i in range(len(x)):
prk = x[i] / self.k
self.sk += prk
last = (self.L - 1) * self.sk
if self.rem != 0:
self.rem = int(last % last)
last = int(last + 1 if self.rem >= 0.5 else last)
self.last_list.append(last)
self.number_of_rows = int(np.ma.count(self.img) / self.img[1].size)
self.number_of_cols = self.img[1].size
for i in range(self.number_of_cols):
for j in range(self.number_of_rows):
num = self.img[j][i]
if num != self.last_list[num]:
self.img[j][i] = self.last_list[num]
cv2.imwrite("output_data/output.jpg", self.img)
def plotHistogram(self):
plt.hist(self.img.ravel(), 256, [0, 256])
def showImage(self):
cv2.imshow("Output-Image", self.img)
cv2.imshow("Input-Image", self.original_image)
cv2.waitKey(5000)
cv2.destroyAllWindows()
if __name__ == "__main__":
file_path = os.path.join(os.path.basename(__file__), "image_data/input.jpg")
stretcher = contrastStretch()
stretcher.stretch(file_path)
stretcher.plotHistogram()
stretcher.showImage()