isodata

level = isodata(I::GMTimage; band=1) -> Int

Compute global image threshold using iterative isodata method.

It can be used to convert an intensity image to a binary image with binarize. level is a normalized intensity value that lies in the range [0 255]. This iterative technique for choosing a threshold was developed by Ridler and Calvard. The histogram is initially segmented into two parts using a starting threshold value such as 0 = 2B-1, half the maximum dynamic range. The sample mean (mf,0) of the gray values associated with the foreground pixels and the sample mean (mb,0) of the gray values associated with the background pixels are computed. A new threshold value 1 is now computed as the average of these two sample means. The process is repeated, based upon the new threshold, until the threshold value does not change any more.

Originaly from MATLAB http://www.mathworks.com/matlabcentral/fileexchange/3195 (BSD, Licenced)

Args

• I::GMTimage: input image of type UInt8.

Kwargs

• band: If the I image has more than one band, use band to specify which one to use.

Returns

An integer value that lies in the range [0 255].

Example

I = gmtread(GMT.TESTSDIR * "assets/coins.jpg");
level = isodata(I, band=1)
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