Hue shade colours

Question

Looking at the plot below, how can I know what colours made the Hue shade?

Plot3D[Cos[x - y + x], {x, -10, 10}, {y, -10, 10}, ColorFunction -> Hue]

I want to have only the RGB or HTML color values used by Hue.

I have copied the colors from rm -rf♦'s answer:

FF0000
FF9800
CCFF00
33FF00
00FF66
00FFFF
0066FF
CB00FE
FF0099
FF0000

but with an imprecise tool; how can I have the correct colors used by Mathematica, when I use the ColorFunction -> Hue command?

Answer 1

The old package Graphics`Colors` had the function HSBColor[], which is exactly what was used before Hue[] became built-in. Here's a slightly tweaked reimplementation of HSBColor[]:

hue[h_?NumericQ, s_: 1, b_: 1] /; 0 <= s <= 1 && 0 <= b <= 1 :=
    Module[{mh = 6 Mod[h, 1], i, f, p, q, t},
           {i, f} = Through[{IntegerPart, FractionalPart}[mh]];
           {p, q, t} = b (1 - s {1, f, 1 - f});
           RGBColor @@ {{b, t, p}, {q, b, p}, {p, b, t},
                        {p, q, b}, {t, p, b}, {b, p, q}}[[i + 1]]]

Compare:

Table[hue[h], {h, 0, 1, 1/6}]
   {RGBColor[1, 0, 0], RGBColor[1, 1, 0], RGBColor[0, 1, 0], RGBColor[0, 1, 1],
    RGBColor[0, 0, 1], RGBColor[1, 0, 1], RGBColor[1, 0, 0]}

Table[ColorConvert[Hue[h], "RGB"], {h, 0, 1, 1/6}]
   {RGBColor[1., 0., 0.], RGBColor[1., 1., 0.], RGBColor[0., 1., 0.], RGBColor[0., 1., 1.],
    RGBColor[0., 0., 1.], RGBColor[1., 0., 1.], RGBColor[1., 0., 0.]}

As further confirmation, you can try doing an RGB component plot for hue[], just like in Sjoerd's answer.

---

Added 1/15/2017

A much more compact implementation of hue[] (adapted from this demo by Quilez) goes like this:

hue[h_?NumericQ, s_: 1, b_: 1] /; 0 <= s <= 1 && 0 <= b <= 1 :=
    Apply[RGBColor, b (1 + s (Clip[Abs[Mod[6 h + {0, 4, 2}, 6] - 3] - 1, {0, 1}] - 1))]

---

It seems your question was altogether different (you really should try writing more clearly); here's a routine to produce hex values from a corresponding color:

colorToHex[col_] :=
     StringJoin["#", IntegerString[Round[255 (List @@ ColorConvert[col, "RGB"])], 16, 2]]

To verify that this works, let's reproduce the hex values of the named browser-supported HTML colors:

cols = Take[First[ColorData["HTML", "Range"]], 7]
   {"AliceBlue", "AntiqueWhite", "Aqua", "Aquamarine", "Azure", "Beige", "Bisque"}

colRGB = ColorData["HTML"] /@ cols
   {RGBColor[0.941176, 0.972549, 1.], RGBColor[0.980392, 0.921569, 0.843137],
    RGBColor[0, 1., 1.], RGBColor[0.498039, 1., 0.831373],
    RGBColor[0.941176, 1., 1.], RGBColor[0.960784, 0.960784, 0.862745],
    RGBColor[1., 0.894118, 0.768627]}

colorToHex /@ colRGB
   {"#f0f8ff", "#faebd7", "#00ffff", "#7fffd4", "#f0ffff", "#f5f5dc", "#ffe4c4"}

Compare with the values listed here.

Answer 2

Hue[x] is equivalent to Hue[x, 1, 1]. You can create a simple "table" of colors mapped to x as:

Graphics[{Hue@#, Disk[], Text[Style[ToString@#, FontColor -> Black, FontSize -> 15]]}] & /@ 
    Range[0, 1, 0.1] // GraphicsRow

If you want the RGB values, use ColorConvert.

Answer 3

ColorConvert[Hue[0.1], "RGB"]

RGBColor[1., 0.6, 0.]

All hues, graphically:

ListLinePlot[
 Table[ColorConvert[Hue[h], "RGB"] /. RGBColor -> List, {h, 0, 1, 0.01}]\[Transpose], 
 PlotStyle -> {Red, Green, Blue}, DataRange -> {0, 1}]

Answer 4

Would ColorData["HTML"] solve your problem? There are 140 colors in that list.

ColorData["HTML", "ColorRules"] // Take[#, 5] & // Column

AliceBlue->RGBColor[0.941176,0.972549,1.]
AntiqueWhite->RGBColor[0.980392,0.921569,0.843137]
Aqua->RGBColor[0,1.,1.]
Aquamarine->RGBColor[0.498039,1.,0.831373]
Azure->RGBColor[0.941176,1.,1.]

Plot3D[Cos[2 x - y], {x, -10, 10}, {y, -10, 10},
 BoxRatios -> {1, 1, .1},
 ColorFunction -> (Hue[#1] &)]

You can color your plot instead of Hue[#1] where #1 is x-coordinate rescaled to interval [0, 1] with the closest RGB color in ColorData["HTML"].

With[{nf = Nearest[
    List @@@ ColorData["HTML", "ColorList"]]},
 Plot3D[Cos[2 x - y], {x, -10, 10}, {y, -10, 10},
  BoxRatios -> {1, 1, .1},
  ColorFunction -> (Apply[RGBColor,
      nf[ColorConvert[Hue[#1], "RGBColor"]][[1]]] &)]]

It looks the same!? It does, but it's colored with those 140 colors. See:

With[{nf = Nearest[
    List @@@ ColorData["GeologicAges", "ColorList"]]},
 Plot3D[Cos[2 x - y], {x, -10, 10}, {y, -10, 10},
  BoxRatios -> {1, 1, .1},
  ColorFunction -> (Apply[RGBColor,
      nf[ColorConvert[Hue[#1], "RGBColor"]][[1]]] &)]]

You may find ColorData["HTML"] useful as well (with 216 distinct shades).

ColorData["WebSafe", "Image"]

Their name is their hex code:

ColorData["WebSafe", "ColorRules"] // Take[#, 7] & // Column

#FFFFFF->RGBColor[1.,1.,1.]
#FFFFCC->RGBColor[1.,1.,0.8]
#FFFF99->RGBColor[1.,1.,0.6]
#FFFF66->RGBColor[1.,1.,0.4]
#FFFF33->RGBColor[1.,1.,0.2]
#FFFF00->RGBColor[1.,1.,0.]
#FFCCFF->RGBColor[1.,0.8,1.]

Answer 5

With newer Mathematica there new function for the task.

From ColorData get "HTML" as the desired scheme. Then use ImageRecolor to exchange the Hue. The need for an appropriate replacement from Hue to RGBColor is easier now.

With ColorConvert this can be done in one single built-in.

Export allows for detailed settings for web optimization for each jpg, png, gif, TIFF. These formats can be checked after reimport by explorative built-ins for example with ImageColorSpace.