Matrix Image Fusion Operation

Does somebody know what imfuse is actually doing? I know it is a composite of an image, but what is the matrix operation of imfuse ? So suppose that I have a matrix A (RGB color 3x uint8) and matrix B (also 3x uint8). So now if I execute:

C = imfuse(A,B)

What does it actually do with A and B? Is it wavelet transform or what?

Thanks in advance.

[Astarag Chattopadhyay]

If you are interested in how the 'imfuse' function is implemented, you can execute 'edit imfuse.m' on your MATLAB command window and go through the MAT file 'imfuse.m'.