how to merge to images to one image?

[michpre]

Hey

I would like to load about 2 BMP frames (2 layers of one image) to device
and then Alpha Blending the layers to one image (ie put image B on top of image A (ex A is a background image and B is animal image))

I have :
img_A_rgb_buffer, img_A_alpha_buffer (set to 255)
img_B_rgb_buffer, img_B_alpha_buffer

I would like to do that (only the Blending) with openGL (in order to get better perfomance)
the output will be a img_out_buffer (the img_out_alpha_buffer is equal to img_B_alpha_buffer)
I dont want to display the image only the Blending and then back the image to save on disk.


Any idea how to do that?
I would appreciate specific just basic code.

Thanks
Miki