Re: [Gegl-developer] Motion blur strange behavior

On Thu, Dec 27, 2012 at 1:38 AM, Pavel Roschin <roshin scriptumplus ru> wrote:
Hello, I noticed two strange things in using gegl's motion blur:

1. Opencl and normal versions are different - try to use ImageMagick's

This is because the OpenCL path doesn't support the new abyss
policies, so it just uses a (0,0,0,0) pixel outside the geglbuffer
boundaries, while the "normal" version is probably using clamp.

2. I have to insert node "crop" because filter produces too big buffer
(bigger than initial image)

I attached test images and source code.

I see too much bugs in filters, that must work with neighborhood
pixels, it seems that this is due to complicated tile nature of gegl...

Yeah... it seems some of the filters are broken, I have to dig up what
is the problem, probably some of the recent changes in GEGL.

And so, some tests:

1. OpenCL version of motion-blur:  1.0 s  (GeForce GT 430,   year 2012)
2. CPU version of motion-blur:     >10 s  (Pentium 4 3.0GHz, year 2003)
3. GIMP's old version motion blur: ~2 s (faster, much faster gegl's)

10x times faster. But my CPU significantly slower and older than GPU.

In this case I hope GIMP will keep his fast (even if 8bit-per-color)
filters, sometimes speed is the main thing in image processing. Or
may be GEGL will have faster operations for 8-bit data?

But that's the point of using the GPU! We can have good and awesome
floating-point precision and speed :)


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