topic Faster Blur using IIR filter in Intel® Integrated Performance Primitives

Faster Blur using IIR filter

Thomas_Jensen1 — Tue, 14 Feb 2006 18:36:13 GMT

(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

Re: Faster Blur using IIR filter

Intel_C_Intel — Tue, 28 Feb 2006 18:00:50 GMT

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

Re: Faster Blur using IIR filter

Thomas_Jensen1 — Sat, 04 Mar 2006 18:02:06 GMT

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

Re: Faster Blur using IIR filter

arataj — Sun, 19 Mar 2006 21:48:58 GMT

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