View License

Download apps, toolboxes, and other File Exchange content using Add-On Explorer in MATLAB.

» Watch video

Highlights from
Faster Kuwahara filter

4.0 | 1 rating Rate this file 12 Downloads (last 30 days) File Size: 2.62 KB File ID: #15027 Version: 1.0
image thumbnail

Faster Kuwahara filter



17 May 2007 (Updated )

Performs a very fast Kuwahara filtering on images.

| Watch this File

File Information

This function performs a Kuwahara filtering on images. It is optimized using vectorization, convolution and the fact that, for every subregion
    variance = (mean of squares) - (square of mean).
A nested-for loop approach is still used in the final part as it is more readable, but a commented-out, fully vectorialised version is provided as well.

This function is about 2.3 times faster than KuwaharaFast at
with a 5x5 window, and even faster at higher window sizes (about 4 times on a 13x13 window)

Kuwahara Filter description
The Kuwahara filter works on a window divided into 4 overlapping subwindows (for a 5x5 pixels example, see below). In each subwindow, the mean and variance are computed. The output value (located at the center of the window) is set to the mean of the subwindow with the smallest variance.

   ( a a ab b b)
   ( a a ab b b)
   (ac ac abcd bd bd)
   ( c c cd d d)
   ( c c cd d d)



This file inspired Super Fast Kuwahara Image Filter (For N Dimensional Real Or Complex Data).

MATLAB release MATLAB 7.4 (R2007a)
Tags for This File   Please login to tag files.
Please login to add a comment or rating.
Comments and Ratings (2)
20 Jul 2013 ashkan abbasi

it works for gray level images.
here is an example:
I_f = Kuwahara(im2double(rgb2gray(I)),5);

see also

02 Dec 2007 Armani Etiquet

Hi how exactly to use this filter? I'm typing :
filtered = Kuwahara(original,5);
in command window, but ir drops me out:
"??? Undefined function or variable 'original'."
i tryed to put image name instrad of 'original' and image with wxtension - it diesn't work always says the same error.
I tryed to put integer value- then, there is no error but dunction does 'nothin'.(no action taken).

Comment only

Contact us