How to merge two images one over another?

Note

1 both are RGB's

2 black area iscompletely black i.e., RGB value is 0

Right now I am doing this:

But I am not satisfied with performance, in terms of time it is taking.

Can there be more efficient way?

[Adam]

im_blank > 0

is going to produce a 3-element vector on an RGB image.

[JAI PRAKASH]

Yes, you are right.

My approach is accurate, but consumes more time.

Answer 1

[OCDER]

I don't think you can go any faster at this point, unless zoom_image is a double. If so, then you can do

zoom_image = zoom_image.*(~mask) + imblank.*mask; % ~17% faster

When you reached the end of the code-based optimization, try parallel or GPU computing, or MEX/C++ to achieve faster speeds. I'm guessing GPU computing is the way to go since GPU is designed for image processing.

https://www.mathworks.com/discovery/matlab-gpu.html

[JAI PRAKASH]

Hey OCDER

Thanx

Can u guide me how to speed up using me c++. Not exactly on above problem but generally how to use mex c++ to speed up calculation.

[OCDER]

Ah, that took me a while to get used to and I'm still learning tricks. The general idea is to make a "gateway" function that links matlab to C++. I started with this tutorial and looked at the example codes that matlab has.

https://www.mathworks.com/help/matlab/matlab_external/standalone-example.html

It's a good investment as some of my codes have been sped up > 10 times, and GPU uses C language. When you get stuck on mex, ask us at the forum. The mvp's have more experience with mex coding.