[Numpy-discussion] Counting the Colors of RGB-Image

Tony Yu tsyu80@gmail....
Sun Jan 15 10:03:29 CST 2012


On Sun, Jan 15, 2012 at 10:45 AM, <apo@pdauf.de> wrote:

>
> Counting the Colors of RGB-Image,
> nameit im0 with im0.shape = 2500,3500,3
> with this code:
>
> tab0 = zeros( (256,256,256) , dtype=int)
> tt = im0.view()
> tt.shape = -1,3
> for r,g,b in tt:
>  tab0[r,g,b] += 1
>
> Question:
>
> Is there a faster way in numpy to get this result?
>
>
> MfG elodw
>

Assuming that your image is made up of integer values (which I guess they'd
have to be if you're indexing into `tab0`), then you could write:

>>> rgb_unique = set(tuple(rgb) for rgb in tt)

I'm not sure if it's any faster than your loop, but I would assume it is.

-Tony
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