Forums > Jitter

gpu-based histogram

February 21, 2006 | 6:32 pm

Is there any way to access the histogram or min/max functions included
in the gl_arb_imaging extension that is a part of opengl? This would
require rasterization, but it might still be faster than going back to
a jit.matrix to perform the histogram analysis on the CPU.

Can this be accessed through glslang through jit.gl.slab? Through an
external? Thanks in advance.

-=jack turner


February 21, 2006 | 7:00 pm

On Feb 21, 2006, at 10:32 AM, Jack Turner wrote:

> Is there any way to access the histogram or min/max functions included
> in the gl_arb_imaging extension that is a part of opengl? This would
> require rasterization, but it might still be faster than going back to
> a jit.matrix to perform the histogram analysis on the CPU.

We don’t currently expose any of the imaging extensions in Jitter,
though a third party extern in theory should be capable of doing this
if the card supports

> Can this be accessed through glslang through jit.gl.slab?

This is something of a tricky thing to implement inside a pixel
shader. It would need to be multi-pass as a histogram in its typical
implementation is a "scatter" algorithm rather than a "gather"
algorithm (the latter being a requirement for stream processing).
However, with multiple passes you can implement a gather algorithm,
though it will be tricky to accomplish.

http://www.google.com/search?q=gpgpu+histogram

-Joshua


February 22, 2006 | 4:04 am

this is a great idea… it would add a lot of value to jitter’s GPU
processing. i’m imagining an on-the-fly autolevels effect. very nice!

i’m officially making a feature request, since i don’t currently have
the proper coding chops. :)

-jlm


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