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From: Bill White <billw@wolfram.com>
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Subject: Re: HTML foreground and background colors being the same... poll time!
Date: 03 Dec 1998 08:56:16 -0600
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In message <199812031400.JAA09195@kramer.bp.aventail.com>,
"William M. Perry" <wmperry@aventail.com> wrote:

> b is pretty easy to implement:
> 
> (defun infer-contrasting-color (r g b)
>   (if (and (<= r 255)
> 	   (<= g 255)
> 	   (<= b 255))
>       (format "#%02x%02x%02x"
> 	      (logxor r 255)
> 	      (logxor g 255)
> 	      (logxor b 255)))
>   (format "#%04x%04x%04x"
> 	  (logxor r 65535)
> 	  (logxor g 65535)
> 	  (logxor b 65535)))

For (r g b) = (127 127 127) this would return (128 128 128) - not
much contrast :-(

bw
-- 
Bill White . billw@wolfram.com . http://www.wolfram.com/~billw
I have discovered a truly wonderful proof of Fermat's Last Theorem,
but unfortunately this .signature is too small to contain it.