plot/

histeq.pro

top source histeq

Plot

result = histeq(image, zeroeq=zeroeq, mapping=mapping)

Performs histogram equalization scaling of a 2D image.

Return value

Result contains a byte-scaled image where the distribution of pixel values is roughly uniform.

Parameters

image in: Input image (for example, as generated with HIST_2D) containing integer or byte values.

Keywords

zeroeq in: Set this keyword to perform equalization using all pixels, even those with a value of zero. Default is to ignore pixels with a zero value.
mapping in: Optional output keyword containing a 256-element array with the original values corresponding to each output value.

Examples

    xpts = randomn(seed, 100000)
    ypts = randomn(seed, 100000)
    im1 = hist_2d(xpts,ypts,min1=-2,max1=2,bin1=0.05,min2=-2,max2=2,bin2=0.05)
    im2 = histeq(im1)
    im1 = bytscl(im1)
    !p.multi = [0,2,2]
    tvim, im1, xrange=[-2,2], yrange=[-2,2], title='Normal'
    plothist, im1, title='Pixel values', bin=10
    tvim, im2, xrange=[-2,2], yrange=[-2,2], title='Histogram-equalized'
    plothist, im2, title='Pixel values', bin=10
    !p.multi = 0

Author information

History:: Writen by: Jeremy Bailin, 9 Dec 2008 Modified 12 Dec 2008 JB: Do not include zero values when performing eq unless /ZEROEQ is set. Modified 26 Sept 2010 Adding MAPPING keyword. 17 June 2011 Efficiency improvement when input values are much greater than 1.

File attributes

Modification date:	Fri Jun 17 12:15:04 2011
Lines:	66

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