OpenCV - Fastest method to check if two images are 100% same or not

问题

There are many questions over here which checks if two images are "nearly" similar or not.

My task is simple. With OpenCV, I want to find out if two images are 100% identical or not.

They will be of same size but can be saved with different filenames.

回答1:

You can use a logical operator like xor operator. If you are using python you can use the following one-line function:

Python

def is_similar(image1, image2):
    return image1.shape == image2.shape and not(np.bitwise_xor(image1,image2).any())

where shape is the property that shows the size of matrix and bitwise_xor is as the name suggests. The C++ version can be made in a similar way!

C++

Please see @berak code.

Notice: The Python code works for any depth images(1-D, 2-D, 3-D , ..), but the C++ version works just for 2-D images. It's easy to convert it to any depth images by yourself. I hope that gives you the insight! :)

Doc: bitwise_xor

EDIT: C++ was removed. Thanks to @Micka and @ berak for their comments.

回答2:

the sum of the differences should be 0 (for all channels):

bool equal(const Mat & a, const Mat & b)
{
    if ( (a.rows != b.rows) || (a.cols != b.cols) )
        return false;
    Scalar s = sum( a - b );
    return (s[0]==0) && (s[1]==0) && (s[2]==0);
}

回答3:

If they are same files except being saved in different file-names, you can check whether their Checksums are identical or not.

回答4:

import cv2
import numpy as np
a = cv2.imread("picture1.png")
b = cv2.imread("picture2.png")
difference = cv2.subtract(a, b)    
result = not np.any(difference)
if result is True:
    print("Pictures are the same")
else:
    print("Pictures are different")

来源：https://stackoverflow.com/questions/23195522/opencv-fastest-method-to-check-if-two-images-are-100-same-or-not

标签

python

c++

OpenCV