HSI Color Coordinate System Conversions
[Color Manipulation]

---

Detailed Description

HSI is just the RGB color space written in a different coordinate system.

"I" is the cube diagonal. HS is a polar coordinates of a plane normal to "I". "S" is the distance from the diagonal. "H" is the angle from red vector.

This is not a new color space, this is exactly the same gammut as RGB.
Since it is still a cube, Smax depends on H.

See im_colorhsi.h

Functions
float	imColorHSI_Smax (float h, double cosh, double sinh, float i)
float	imColorHSI_ImaxS (float h, double cosh, double sinh)
void	imColorRGB2HSI (float r, float g, float b, float *h, float *s, float *i)
void	imColorRGB2HSIbyte (unsigned char r, unsigned char g, unsigned char b, float *h, float *s, float *i)
void	imColorHSI2RGB (float h, float s, float i, float *r, float *g, float *b)
void	imColorHSI2RGBbyte (float h, float s, float i, unsigned char *r, unsigned char *g, unsigned char *b)

---

Function Documentation

float imColorHSI_Smax (  float  h, double  cosh, double  sinh, float  i )

Returns the maximum S for H (in radians) and I.

float imColorHSI_ImaxS (  float  h, double  cosh, double  sinh )

Returns I where S is maximum given H (in radians).

void imColorRGB2HSI (  float  r, float  g, float  b, float *  h, float *  s, float *  i )

Converts from RGB to HSI.

void imColorRGB2HSIbyte (  unsigned char  r, unsigned char  g, unsigned char  b, float *  h, float *  s, float *  i )

Converts from RGB (byte) to HSI.

void imColorHSI2RGB (  float  h, float  s, float  i, float *  r, float *  g, float *  b )

Converts from HSI to RGB.

void imColorHSI2RGBbyte (  float  h, float  s, float  i, unsigned char *  r, unsigned char *  g, unsigned char *  b )

Converts from HSI to RGB (byte).