Many colors in the device independent colors spaces, such as CIE Lab, cannot be exactly represented in RGB and displayed on a monitor.  The ToDisplayable command computes a nearby color that can be represented in RGB and thus displayed.

A color object that is not exactly displayable will be displayed with asterisks around the color space when the color object is printed.

By default a nearby color is determined by moving along the line towards the 50% gray in the CIE XYZ color space until a displayable color is reached. This can be specified explicitly by specifying the option mode = "XYZ".

Specifying mode = "Lab" will instead move along the line towards the neutral gray point in the CIE Lab color space that has the same L-coordinate as color.

Specifying mode = "HSV" will preserve the hue and truncate the saturation and value coordinates of color in the HSV color space to the range 0..1.

Specifying mode = "RGB" will truncate each of the coordinates of color in the RGB color space to the range 0..1.

Specifying mode = "RGBscale" will represent color in the RGB color space, then add the same minimal positive constant to each coordinate that makes all entries non-negative, and finally, if necessary, divide each coordinate by the maximal coordinate, so that the coordinates are all in the range 0..1.

$\mathrm{with}\left(\mathrm{ColorTools}\right)\:$

$C≔\mathrm{Color}\left(\left[0.293\,-0.128\,0.132\right]\right)$

$C≔⟨*RGB*\; :\; 0.293\; -0.128\; 0.132⟩$

$\mathrm{C1}≔\mathrm{ToDisplayable}\left(C\right)$

$\mathrm{C1}≔⟨RGB\; :\; 0.215\; -0.00176\; 0.115⟩$

$\mathrm{C2}≔\mathrm{ToDisplayable}\left(C\,\mathrm{mode}=''Lab''\right)$

$\mathrm{C2}≔⟨RGB\; :\; 0.215\; -0.00176\; 0.115⟩$

$\mathrm{C3}≔\mathrm{ToDisplayable}\left(C\,\mathrm{mode}=''HSV''\right)$

$\mathrm{C3}≔⟨RGB\; :\; 0.293\; 0\; 0.181⟩$

$\mathrm{C4}≔\mathrm{ToDisplayable}\left(C\,\mathrm{mode}=''RGB''\right)$

$\mathrm{C4}≔⟨RGB\; :\; 0.293\; 0\; 0.132⟩$

$\mathrm{C5}≔\mathrm{ToDisplayable}\left(C\,\mathrm{mode}=''RGBscale''\right)$

$\mathrm{C5}≔⟨RGB\; :\; 0.421\; 0\; 0.26⟩$

$\mathrm{Swatches}\left(\left[\mathrm{C1}\,\mathrm{C2}\,\mathrm{C3}\,\mathrm{C4}\,\mathrm{C5}\right]\,\mathrm{rows}=1\right)$

The ColorTools[ToDisplayable] command was introduced in Maple 18.

For more information on Maple 18 changes, see Updates in Maple 18.