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Re: Determine brightness of colour/Convert to GrayLevel

• To: mathgroup at smc.vnet.net
• Subject: [mg89512] Re: [mg89485] Determine brightness of colour/Convert to GrayLevel
• From: "Szabolcs HorvÃt" <szhorvat at gmail.com>
• Date: Wed, 11 Jun 2008 03:19:49 -0400 (EDT)
• References: <200806101114.HAA18927@smc.vnet.net> <484E695C.6070909@wolfram.com>

On Tue, Jun 10, 2008 at 14:45, Carl Woll <carlw at wolfram.com> wrote:
> 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.
>

Thanks!  That's exactly what I was looking for.

• References:
  • Determine brightness of colour/Convert to GrayLevel
    • From: "Szabolcs HorvÃt" <szhorvat@gmail.com>