MINMAX

NAME
SYNOPSIS
INPUT PARAMETERS
OUTPUT PARAMETERS
DESCRIPTION
EXAMPLE
REFERENCES
AUTHORS
AVAILABILITY
SEE ALSO

NAME

minmax - Min/Max algorithm for noise removal from images

SYNOPSIS

Output = minmax(Input, [NSteps, StepSize, Adapt, NonAdaptThreshold,
                  IntMaskSize, ExtMaskSize])

INPUT PARAMETERS

Input

a matrix containing a gray-scale image to be filtered by min/max algorithm.

NSteps

number of steps to perform. Default is 10.

StepSize

the step increment for the iterative procedure. Default is 0.05.

Adapt

indicates if the algorithm should adapt itself to the local image gray level or if it considers the NonAdaptThreshold value for defining light and dark regions. Default is FALSE.

NonAdaptThreshold

If Adapt is FALSE, intensity values greater than NonAdaptThreshold will be considered as light regions.

IntMaskSize

Size of the Internal window in which curvature values will be taken into account for deciding Min or Max curvature flow. Default is 1.

ExtMaskSize

Size of the External window in which curvature values will be taken into account for deciding Min or Max curvature flow in the Adapt mode. Default is 0.

OUTPUT PARAMETERS

Output

a matrix containing the filtered image.

DESCRIPTION

Function minmax filters a gray-scale image using curvature-guided surface evolution. Object borders remain sharp while low-scale noise is removed.

EXAMPLE

M = gray_imread(SIPDIR+'images/noisypoly.bmp');
subplot(1,2,1);
imshow(M);
new_M = minmax(M, NSteps=30);
subplot(1,2,2);
imshow(new_M);

REFERENCES

"Image Processing via Level Set Curvature Flow ", Malladi, R., and Sethian, J.A., Proceedings of the National Academy of Sciences, Vol. 92(15), pp. 7046-7050, July 1995
http://math.berkeley.edu/~sethian/Movies/Movienoiseremoval.html

AUTHORS

Leandro Estrozi (lfestrozi@if.sc.usp.br)

AVAILABILITY

The latest version of the Scilab Image Processing toolbox can be found at

http://siptoolbox.sourceforge.net