[PyOpenGL-Users] Newbie question - multiplying gl matrices element-wise

[Brendan S. <bre...@ya...>]

Hi all,

Sorry for the basic level of this question.  I'm absolutely new to GL  
programming.  I'm trying to implement a very simple demosaicing  
algorithm on the graphics card (in order to render data from a really  
high-res bayer-filtered ccd sensor to the screen in real time).  I  
need to be able to do the following:

1) given a "raw" image, copy the data (a matrix of unsigned bytes) to  
video memory three times.

2) multiply each copy element-wise by a precomputed "mask" of 1s and  
0s, so that the first copy records only the red values (all others  
become 0), the second green, and the last blue.

3) Interpolate the missing colour info.  This step is different for  
green, and for red/blue, but it goes something like this:   Copy a  
crop of the green matrix exactly one row and one column narrower on  
all sides.  Now add (again element-wise) to that copy another crop of  
the green matrix, but this time shifted up one row.  And again shifted  
down one row.  And again shifted left on column.  And one more shifted  
right one column.  Divide the total (element-wise) by 4.

4) Copy the interpolated red, green and blue matrices to an opengl  
texture.  Map the texture to a 2d square, and render the square to the  
screen (resizing / rotating / flipping as desired).

I can figure out steps 1 and 4.  Ideally steps 2 and 3 would be done  
in video memory, using opengl functions, but I can't find anything  
that would do element-wise multiplication, addition or cropping of  
matrices in the opengl stack.   Can anyone point me in the right  
direction?

Thanks,
  Brendan
--
Brendan Simons