how i can superpose (overlay) two images ?

Hello

how i can superpose (overlay) two images with different size and find the différence?

Thanks

Answer 1

[DGM]

You can use tools like imoverlay() or imfuse(), or you can combine the images by opacity blending.

There are other ways "overlay" can be interpreted, so you might want to clarify what kind of images you're dealing with and what you expect the result to be. Tools like imoverlay() might not work if neither image is binarized. Imfuse() may not be helpful if you want opacity blending for any alpha value other than 0.5.

This is basic opacity blending

FG = imread('cameraman.tif');
BG = imread('cmantifBG.png');
montage({FG BG})

a = 0.6; % foreground opacity
C = a*FG + (1-a)*BG;

imshow(C)

In image manipulation applications, 'overlay' might mean something entirely different:

C = imblend(FG,BG,1,'overlay'); % THIS IS A MIMT-ONLY TOOL (see file exchange)

Furthermore, it's conceivable that you want to combine two non-binarized images with the aid of a mask. Depending on what you want, this may be a logical or linear combination.

In all cases, it's expected that the images have the same geometry. If they don't, you'll have to figure out how you want to colocate them and then continue as before. Here's another example:

https://www.mathworks.com/matlabcentral/answers/1615875-merging-two-images-with-background

TL;DR: It depends.

[qc qcc]

I have a snapshot with my camera and the second image from the code-G. I want to overlay and find the différence

Thanks.

[qc qcc]

Arrays have incompatible sizes for this operation.

[DGM]

Yes. They're incompatible because they're not the same size. You'll have to align them and make them the same size.

I don't know if you added those images or if I just overlooked them, but this is a way to get the absolute difference via imfuse():

A = imread('https://www.mathworks.com/matlabcentral/answers/uploaded_files/917734/ttest.JPG');
B = imread('https://www.mathworks.com/matlabcentral/answers/uploaded_files/917729/ttest1.JPG');

A = A(3:end-1,1:end-2,:);

D = imfuse(A,B,'diff');

imshow(D)

[qc qcc]

how i can make them with the same size

[DGM]

In the given example, I manually aligned them by cropping. As given, this attempts to align the square in the center region.

A generalized and automatic registration process would require a better understanding of the expectations regarding what might be presented and what's important to align. Registration accuracy would likely be hindered by the noise produced by compression.