Overlapping binary files with QByteArray stream

I have two binary files, of which I have no clue about their data organization. I have them as QByteArray stream and overlap them meaning a[i]=b[i]+c[i].

I made an attempt with

QByteStream x,y,z
for(k=0;k<x.size();k++){
for(l=0;l<y.size();l++){
if(k=l){
z[k]=x[k]+y[l];
z.append(z[k]);
}
}
}

I know that it was a naive attempt but couldn't do more as I have no clue about the internal data organization, all I know is they are binary. Any suggestions or help please !!

And what's the question/problem?

I have to overlap two images in binary format.

If you don't know nothing about the images, and you can't process their headers (or there is no headers) then my guess is that you can't do it.

Please do not ask the same question in multiple places