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Re: Determine brightness of colour/Convert to GrayLevel

  • To: mathgroup at smc.vnet.net
  • Subject: [mg89509] Re: [mg89485] Determine brightness of colour/Convert to GrayLevel
  • From: Carl Woll <carlw at wolfram.com>
  • Date: Wed, 11 Jun 2008 03:19:12 -0400 (EDT)
  • References: <200806101114.HAA18927@smc.vnet.net>

Szabolcs Horvát wrote:

>Colours have several representations, such as RGBColor, CMYKColor,
>GrayLevel, etc.
>
>Is there a way to convert between these representations?  More
>specifically is there a way to convert a colour to GrayLevel?  I would
>like to determine the "brightness" of a colour to decide whether to
>display text in black or in white on top of it.
>
>Also, is there a way to convert a colour to some canonical
>representation?  A workaround I found is Lighter[colour, 0], which
>converts to RGBColor, but I was hoping that there exists a function
>meant specifically for conversion (and not
>blending/lightening/darkening).
>  
>
Try ToColor:

?ToColor

ToColor[color, form] converts color to form if form is GrayLevel, 
RGBColor or CMYKColor. Otherwise form[color] is evaluated and the result \
is expected to be a valid color directive.

Carl Woll


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