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rgbhsv

Converts RGB color values to HSV.

Available in version 5.0.0 and later.

Prototype

	function rgbhsv (
		rgb  : numeric   
	)

	return_val  :  numeric

Arguments

rgb

An array of Red, Green, Blue (RGB) color values. This array can be of any shape, but the rightmost dimension must be 3 for specifying the RGB values. The Red, Green, and Blue values are intensities in the range [0.,1.].

Return value

The returned value is an array of the same dimensions and dimension sizes as the input array. The input RGB values will have been replaced with their Hue, Saturation, Value (HSV) equivalents. If any values in the input array are double precision, the returned array will be double precision.

Description

This function determines the HSV equivalents to RGB color values.

The returned Hue values will be in the range [0., 360.). A value of (R,0.,0.) in the input RGB space will result in a Hue of 0. in the HSV space.

The returned Saturation values will be in the range [0.,1.]. Saturation is a measure of how much white light is mixed with the color. Saturation values of 0. represent greys (with a grey value equal to V). Saturation values of 1. are fully saturated colors. The hue is technically undefined when S=0; the code leaves H at its previous value when S=0. (0. initially). The fully saturated pure hues occur when S=1. and V=1.

The returned Value values will be in the range [0.,1.].

For a complete description of the algorithm see:

  1. Foley, James D. and van Dam, Andries,"Fundamentals of Interactive Computer Graphics",Addison-Wesley Publishing Company, 1982.

Missing values are not honored as such.

See Also

hsvrgb, hlsrgb, rgbhls, yiqrgb, rgbyiq

Examples

Example 1

The following:

begin
  hsv = rgbhsv((/1.0d, 0.0d, 0.0d/))
  print(hsv)
end
produces:

Variable: hsv
Type: double
Total Size: 24 bytes
            3 values
Number of Dimensions: 1
Dimensions and sizes:   [3]
Coordinates: 
(0)        0
(1)        1
(2)        1
Example 2

The following:

begin
  rgb = (/                                             \
           (/(/1.d, 0.d, 0.d/), (/0.d, 1.d, 0.d/)/),   \
           (/(/0.d, 0.d, 1.d/), (/1.d, 1.d, 0.d/)/),   \
           (/(/1.d, 0.d, 1.d/), (/0.d, 1.d, 1.d/)/)    \
        /)
  hsv = rgbhsv(rgb)
  print (hsv)
end

produces:

Variable: hsv
Type: double
Total Size: 144 bytes
            18 values
Number of Dimensions: 3
Dimensions and sizes:   [3] x [2] x [3]
Coordinates: 
(0,0,0)    0
(0,0,1)    1
(0,0,2)    1
(0,1,0)  120
(0,1,1)    1
(0,1,2)    1
(1,0,0)  240
(1,0,1)    1
(1,0,2)    1
(1,1,0)   60
(1,1,1)    1
(1,1,2)    1
(2,0,0)  300
(2,0,1)    1
(2,0,2)    1
(2,1,0)  180
(2,1,1)    1
(2,1,2)    1