[Image-SIG] Faster way to examine alpha ?

Ray Pasco pascor at hotpop.com
Fri Apr 1 18:59:52 CEST 2005

I have a routine that examines the alpha values of an RGBA image to 
whether whether there are any "active"alpha (value < 255), and
whether the any active alpha are single-valued and if only a single color
is associted with this alpha. Each pixel must be examined one-by-one
which is rather slow.

Is there way to examine pixel values akin to the .point(lambda) method ?
I just want to examine, not change the valuse.

Ray Pasco

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