How to do median filter on an indexed image using MATLAB?

medfilt2(img) doesn't take a map as parameter,

so I don't think it can work well with indexed image,

how do I impelemnt an median filter that can b开发者_如何学Goe used to process indexed images?

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From the medfilt2 documentation:

B = medfilt2(A, 'indexed', ...) processes A as an indexed image, padding with 0s if the class of A is uint8, or 1s if the class of A is double.