how to copy and paste image to other figure?

Hi, I create a color plot in figure A as

A=rand(512,512);
pcolor(A); shading flat;
axis off;
axis image;

Then I click the image and copy it. I have a figure B (already has some plot there). I am going to paste the selected image to B and make it smaller as inset. But I found that when I paste the image, it will create a axis and there show some margin between the image and the axis. I cannot change the size of the paste image. How can I copy and paste the image only (not include the axis) and I can freely change the size of the paste image? Thanks.