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IM: HSI Color Coordinate System Conversions

From IM - An Imaging Tool

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HSI Color Coordinate System Conversions
[Color Manipulation]

Detailed Description

HSI is just the RGB color space written in a different coordinate system.
"I" is defined along the cube diagonal. It ranges from 0 (black) to 1 (white).
HS are the polar coordinates of a plane normal to "I".
"S" is the normal distance from the diagonal of the RGB cube. It ranges from 0 to Smax.
"H" is the angle starting from the red vector, given in degrees.
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 (here in radians) and I.

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

Returns I where S is maximum given H (here 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).


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