how to calculate degree of similarity between two images

i wanna know if there is a way to calculate degree of similarity between two images?

Answer 1

[Image Analyst]

ssimval = ssim(A,ref) computes the Structural Similarity Index (SSIM) value for image A using ref as the reference image.

peaksnr = psnr(A,ref) calculates the peak signal-to-noise ratio for the image A, with the image ref as the reference. A and ref must be of the same size and class.

err = immse(X,Y) calculates the mean-squared error (MSE) between the arrays X and Y. X and Y can be arrays of any dimension, but must be of the same size and class.

[bay rem]

is it right for both two lastest examples to resize the second image as the size of the image ref?

[Image Analyst]

Yes

[J Parker]

I looked into those methods, but they only give a scalar value and I am interested in determining the similarity for each element in a column. I thought using the euclidean distance and Gaussian similarity measure would work.

[Image Analyst]

So you want to determine similarity on a pixel-by-pixel basis and get a number for each pair of pixels. Given only two numbers, say 49 and 158 for example, how do you determine the difference, given no other information and assumptions? The only way I can think of is to subtract them. You could take the absolute value of that as the Euclidean distance.

absDiffImage = imabsdiff(image1, image2);

[J Parker]

Great, thanks! But, once I take the Euclidean distance, how do I incorporate it into a Gaussian measure?

[Image Analyst]

I don't know what that means.

[Peter Kamfor]

lol if Image Analyst doesn't know... It probably doesn't even exists. Spent a month with his comments which were the biggest help in my assignment.

[nor azam]

can you explain this part:

err = immse(X,Y)

is it use for image A or both A & Ref image?

[Image Analyst]

X is your "test" image, and Y is your reference image.

[Bhawandeep Sharma]

Is there any other way to analyse 2 images?

[RAKESH KUCHANA]

I am unable to find Similarity Index of two images in MATLAB R2013a version. Can anyone help me regarding this?

[Image Analyst]

Yes, these people can : Click Here

or here:

https://www.mathworks.com/matlabcentral/answers/250430-how-do-i-buy-a-matlab-license?s_tid=srchtitle