www.pudn.com > partsumhist.rar > HSI.cpp

/**$6 
 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 
 * 
 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 
 */ 
 
#include "stdafx.h" 
#include "HSI.h" 
#include  
 
#ifdef _DEBUG 
#define new DEBUG_NEW 
#undef THIS_FILE 
static char THIS_FILE[] = __FILE__; 
#endif 
#define DEGREES_PER_RADIAN	(180.0 / 3.14159265358979) 
 
// define UNDEFINED_HUE -1.000 
#define UNDEFINED_HUE	0.000 
#define ZERO_SATURATION 0.0 
 
/** 
 ======================================================================================================================= 
 * 
 ======================================================================================================================= 
 */ 
 
int RgbToHsi(RGB *RgbPtr, HSI *HsiPtr) 
{ 
	double	R, G, B, Sum, Quotient; 
	double	Radians, Angle, MinValue, MaxValue, TempDouble1, TempDouble2; 
	R = ((double) RgbPtr->r) / 255.0; 
	G = ((double) RgbPtr->g) / 255.0; 
	B = ((double) RgbPtr->b) / 255.0; 
	Sum = R + G + B; 
	HsiPtr->Intensity = Sum / 3.0; 
	MinValue = (R < G) ? R : G; 
	MinValue = (B < MinValue) ? B : MinValue; 
	MaxValue = (R > G) ? R : G; 
	MaxValue = (B > MaxValue) ? B : MaxValue; 
	if(HsiPtr->Intensity < 0.00001) 
		HsiPtr->Saturation = ZERO_SATURATION; 
	else 
		HsiPtr->Saturation = 1.0 - (3.0 * MinValue) / Sum; 
	if(MinValue == MaxValue) 
	{ 
		HsiPtr->Hue = UNDEFINED_HUE; 
		HsiPtr->Saturation = ZERO_SATURATION; 
		return 0; 
	} 
 
	TempDouble1 = (((R - G) + (R - B)) / 2.0); 
	TempDouble2 = (R - G) * (R - G) + (R - B) * (G - B); 
	Quotient = (TempDouble1 / sqrt(TempDouble2)); 
	if(Quotient > 0.99999999999999999) 
		Radians = 0.0; 
	else if(Quotient < -0.99999999999999999) 
		Radians = 3.1415926535; 
	else 
		Radians = acos(TempDouble1 / sqrt(TempDouble2)); 
	Angle = Radians * DEGREES_PER_RADIAN; 
	if(B > G) 
		HsiPtr->Hue = 360.0 - Angle; 
	else 
		HsiPtr->Hue = Angle; 
	return 0; 
}