Histogram and Histogram Equalization of an image

Aim

To obtain a histogram for finding the frequency of pixels in an Image with pixel values ranging from 0 to 255. Also write the code using OpenCV to perform histogram equalization.

Software Required:

Anaconda - Python 3.7

Algorithm:

Step1:

Import the necessary libraries and read two images, Color image and Gray Scale image.

Step2:

Calculate the Histogram of Gray scale image and each channel of the color image.

Step3:

Display the histograms with their respective images.

Step4:

Equalize the grayscale image.

Step5:

Display the grayscale image.

Program:

# Developed By: Revathi Dayalan
# Register Number: 212221240045


# Write your code to find the histogram of gray scale image and color image channels.
import cv2
import matplotlib.pyplot as plt
Gray_image=cv2.imread('parrot.png')
plt.imshow(Gray_image)
plt.show()
hist=cv2.calcHist([Gray_image],[0],None,[256],[0,256])
plt.figure()
plt.title("Histogram")
plt.xlabel('grayscale value')
plt.ylabel('pixel count')
plt.stem(hist)
plt.show()


# Display the histogram of gray scale image and any one channel histogram from color image
import cv2
import matplotlib.pyplot as plt
Color_image=cv2.imread('dog.jpg')
plt.imshow(Color_image)
plt.show()
hist1=cv2.calcHist([Color_image],[1],None,[256],[0,256])
plt.figure()
plt.title("Histogram")
plt.xlabel('Intensity value')
plt.ylabel('pixel count')
plt.stem(hist1)
plt.show()



# Write the code to perform histogram equalization of the image. 
import cv2
Gray_image=cv2.imread('parrot.png',0)
equ=cv2.equalizeHist(Gray_image)
cv2.imshow('Gray Image',Gray_image)
cv2.imshow('Equalized Image',equ)
cv2.waitKey(0)
cv2.destroyAllWindows()

Output:

Input Grayscale Image and Color Image

Histogram of Grayscale Image and any channel of Color Image

Histogram Equalization of Grayscale Image

Result:

Thus the histogram for finding the frequency of pixels in an image with pixel values ranging from 0 to 255 is obtained. Also,histogram equalization is done for the gray scale image using OpenCV.

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