Re: Convert Hue[] to RGBColor[] and backwards
- To: mathgroup at smc.vnet.net
- Subject: [mg103468] Re: Convert Hue[] to RGBColor[] and backwards
- From: "Alexey Popkov" <lehin.p at gmail.com>
- Date: Wed, 23 Sep 2009 07:25:33 -0400 (EDT)
- References: <BLU0-SMTP4514449534FFC9FA25CF7EADC0@phx.gbl>
- Reply-to: "Alexey Popkov" <lehin.p at gmail.com>
Thank you. It is just that I need.
----- Original Message -----
From: "Alexander Elkins" <alexander_elkins at hotmail.com>
To: <hanlonr at cox.net>; <lehin.p at gmail.com>
Sent: Wednesday, September 23, 2009 2:32 AM
Subject: [mg103468] Re: Convert Hue[] to RGBColor[] and backwards
> ?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.
>
> In both v6 and v7 form can also be Hue. For example:
> In[1]:= ToColor[Hue[0.1333333, 0.625, 0.8], RGBColor]
> Out[1]= RGBColor[0.8, 0.7, 0.3]
>
> In[2]:= ToColor[RGBColor[0.8, 0.7, 0.3], Hue]
> Out[2]= Hue[0.133333, 0.625, 0.8]
>
> Of course it is possible to roll one's own ToHue function:
>
> In[3]:= ToHue[color_RGBColor] := Module[{rgb, m, n}, rgb = Clip[#, {0, 1}]
> &
> /@ color;
> m = Max @@ rgb + 0.; n = Min @@ rgb;
> If[m == n, Hue[0., 0., m],
> Hue[Function[{r, g, b},
> Which[r == m, Mod[(g - b)/(m - n), 6], g == m, (b - r)/(m - n) + 2,
> True, (r - g)/(m - n) + 4]/6] @@ rgb, 1 - n/m, m]]];
>
> In[4]:= ToHue[RGBColor[0.8, 0.7, 0.3]]
> Out[4]= Hue[0.133333, 0.625, 0.8]
>
> - Alexander Elkins
>
> "Bob Hanlon" <hanlonr at cox.net> wrote in message
> news:h97msg$7fi$1 at smc.vnet.net...
>>
>> In v7 there is ColorConvert
>>
>> Table[ColorConvert[Hue[h], "RGBColor"], {h, 0, 1, 0.1}]
>>
>>
> {RGBColor[1.,0.,0.],RGBColor[1.,0.6,0.],RGBColor[0.8,1.,0.],RGBColor[0.2,1.,
> 0.],RGBColor[0.,1.,0.4],RGBColor[0.,1.,1.],RGBColor[0.,0.4,1.],RGBColor[0.2,
> 0.,1.],RGBColor[0.8,0.,1.],RGBColor[1.,0.,0.6],RGBColor[1.,0.,0.]}
>>
>> ColorConvert[#, "Hue"] & /@ %
>>
>>
> {Hue[0.,1.,1.],Hue[0.1,1.,1.],Hue[0.2,1.,1.],Hue[0.3,1.,1.],Hue[0.4,1.,1.],H
> ue[0.5,1.,1.],Hue[0.6,1.,1.],Hue[0.7,1.,1.],Hue[0.8,1.,1.],Hue[0.9,1.,1.],Hu
> e[0.,1.,1.]}
>>
>> As can be seen, the conversions are somewhat approximate.
>>
>>
>> Bob Hanlon
>>
>> ---- Alexey Popkov <lehin.p at gmail.com> wrote:
>>
>> =============
>> Hello,
>> I have not found in the Documentation any information on relation
>> between Hue[] and RGBColor[] representations of color. How can I
>> convert one to another?
>>
>>
>>
>>
>> --
>>
>> Bob Hanlon
>>
>>
>
>
>