CImCombine:AlphaClip

The AlphaClip method merges the pixel values using alpha-clipping to remove high and low outlying values at each location. At each pixel location, the images with the nHigh highest pixel values and nLow lowest pixel values are rejected from the sample before computing the mean value for the output image. For the AlphaClip method to work properly, the images must be normalized; this can be done by the combining process..

Syntax

CImage = CImCombine:AlphaClip( CImageSet, nHigh, nLow )

bullet.gif    CImageSet contains the collection of images to be combined.

bullet.gif    nHigh is the number of highest pixel values to exclude.

bullet.gif    nLow is the number of lowest pixel values to exclude.

bullet.gif    CImage is a new image created by this method.

bullet.gif    On success, this method returns a new CImage.

bullet.gif    On failure, this method returns nil.

Example

Suppose a CImageSet named S exists. The following script combines the images by the AlphaClip method by excluding the 2 highest and 1 lowest values from the sample at each location. The images are normalized by the Median statistic computed inside the central 10% of the image:

C = new_imcombine()

-- create a CImCombine object

R = new_rect(10,50,10,50)

-- central 10% of the image

C:SetRelRect( R )

-- specify CImage and CRect to measure

C:SetNormStat("median")

-- use the AlphaClip as the normalization statistic

C:SetNormMethod("scale")

-- scale to normalize the image set

I = C:AlphaClip(S,2,1)

-- combine the image set and return a new image

I:Display()

-- show the new image

C:delete()

-- when done with S, remove it from memory

Related Topics

CImCombine class

CImageSet class

CImage class

CRect class

SdevClip


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