How do I overlap 2 images in matlab?

Hi, all

There are two images of size M X N shown below.

(left image source: https://commons.wikimedia.org/wiki/File:International_10-20_system_for_EEG-MCN.svg)

In fact, my purpose was to create a topomap for the EEG signal, but it was difficult to use a known tool (e.g. EEGLAB), so I made it myself.

How do I make the black part in the right picture transparent and then overwrite the left picture? Or I would like to know how to show them at the same time.

The purpose is to make the following through two images.

Answer 1

[David Hill]

Assuming the pictures are rgb matrixes.

picture2=reshape(picture2,[],3);
idx=ismember(picture2,[0 0 0],'rows');%find the black (I am assuming your image has no true black in the interior)
picture2(idx,:,:)=255;%change the black to white
picture2=reshape(picture2,size(picture1));%reshape to original matrix size
newPicture=min(picture1,picture2);%since picture1 is just black and white taking the minimum will produce the black of picture 1 overlayed on picture2

[jinwoo lee]

Thanks for any help. My one is not an rgb matrix, so I solved it in a different way.