[Octave-bug-tracker] [bug #54567] median(uint8) gives bad results

[Dan Sebald]

Follow-up Comment #1, bug #54567 (project octave):

The question is whether Matlab does the arithmetic using the intrinsic
variable type.  The median() routine is supposed to return the same variable
type, but that doesn't necessarily mean the average of the center values
should be computed using that type.  Why should it, I guess?  In fact, mean()
appears to do its arithmetic not using native, but instead converts it
afterward:


octave:12> u = [1 140 140 255];
octave:13> u8 = uint8(u);
octave:14> mean(u)
ans =  134
octave:15> mean(u8)
ans =  134


So, attached a patch to change the behavior for median.  Basically it uses
mean() instead of sum() with the assumption that the proper averaging behavior
is already baked into mean().  I added a couple more tests as well.

(file #44857)
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Additional Item Attachment:

File name: octave-median_even_averaging-djs2018aug24.patch Size:1 KB


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