Added PSNR calculator for image compression quality analysis (TheAlgorithms#475)

* Added PSNR calculator for image compression quality analysis

* Removed unused variables and redundancy

Author: vasutomar

Analysis/Compression_Analysis/PSNR.py

@@ -0,0 +1,38 @@
+import numpy as np
+import math
+import cv2
+
+def Representational(r,g,b):
+	return (0.299*r+0.287*g+0.114*b)
+
+def calculate(img):
+	b,g,r = cv2.split(img)
+	pixelAt = Representational(r,g,b)
+	return pixelAt
+
+def main():
+	
+	#Loading images (orignal image and compressed image)
+	orignal_image = cv2.imread('orignal_image.png',1)
+	compressed_image = cv2.imread('compressed_image.png',1)
+
+	#Getting image height and width
+	height,width = orignal_image.shape[:2]
+
+	orignalPixelAt = calculate(orignal_image)
+	compressedPixelAt = calculate(compressed_image)
+
+	diff = orignalPixelAt - compressedPixelAt
+	error = np.sum(np.abs(diff) ** 2)
+
+	error = error/(height*width)
+
+	#MSR = error_sum/(height*width)
+	PSNR = -(10*math.log10(error/(255*255)))
+
+	print("PSNR value is {}".format(PSNR))
+
+
+if __name__ == '__main__':
+	main()
+