prgb2hsi

Synopsis

Description

prgb2hsi converts color image from the color space RGB (Red, Green, Blue) to the color space HSI (Hue, Saturation, Intensity).

Hue refers to the gradation of color within the visible spectrum, or optical spectrum, of light. It is expressed in degree unit [0..360].

Saturation or purity is the intensity of a specific hue: a highly saturated hue has a vivid, intense color, while a less saturated hue appears more muted and gray. With no saturation at all, the hue becomes a shade of gray. It is expressed as percentage [0..100].

Lightness is the amount of light in a color. It is expressed in gray level unit [0..255].

The output image is a float image.

The transformation from RGB to HSI is:

           [         ((R-G)+(R-B))            ]
  H = acos [ -------------------------------  ]
           [ 2*sqrt((R-G)*(R-G) + (R-B)(G-B)) ]
  S = 1 - 3*MIN(R,G,B)
          ------------
          (R + G + B)
  I = (R + G + B)/3

Inputs

• im_in: a RGB color image.

Outputs

• im_out: a HSI color image.

Result

Returns SUCCESS or FAILURE.

Examples

Converts parrot.pan from rgb to hsi and conversely.

   prgb2hsi parrot.pan a.pan
   phsitorgb a.pan b.pan

See also

C++ prototype