Faster Blur using IIR filter

[Thomas_Jensen1]

(Ipp 5.0)

I need to blur a 16u pixel buffer using a gaussian kernel.

I have noticed that blurring with IIR much faster is than with a matrix filter.

Do you have an example of blurring with IIR?

Thomas

[Intel_C_Intel]

Hi,

Your could try fast ipp separable filters

ippiFilterRow/ColumnBorderPipeline

the example 9-3 in vol 2 of manual shows how to do it without the extra image. But these functions work with 8u/16s/32f images

Thanks,

Alexander

[Thomas_Jensen1]

Thanks for the tip.

In the mean time, I implemented my own IIR blurring by gaussian.

The code is very fast when burring with large matrices (100x100).

For other sharpening code I use, I will try to move from 17x17 to separable row/column mode, to speed that up. I use a LoG (unsharp mask) matrix, but it could need some speedup.

Thomas

[arataj]

Hello!



I do not exactly know what the IIR Gaussian blur is, but I use one, from GIMP. There are two problems with it:



1) it is increassingly imprecise for larger pixel values,



2) I do not understand its stddev computation:



vert = fabs (vert) + 1.0;

std_dev = sqrt (-(vert * vert) / (2 * log (1.0 / 255.0)));



where `vert' is defined as a radius in the GUI. What is 255 doing there?



The equation changes radius = 1 to stddev = about 0.3. Is it then right to say that I used an approx. of Gaussian blur with stddev = 0.3 with that method?



Best regards,

Artur

Message Edited by arataj on 03-19-200605:50 AM