RGB与HSI空间相互转化 C++

void HSItrans(char tp)
{
/*
** input: tp
** tp--varible of char type,it is used to judge whether HSI-RGB or RGB-HSI.
** h:[0,360]
** s:[0,1]
** I:[0,1]

** r:[0,255]
** g:[0,255]
** b:[0,255]
*/

if (myHSIArray==NULL) myHSIArray= new sHSI[myPHeight*myPWidth];

double tH,tS,fR,fG,fB;
BYTE R,G,B,tI;
int i,j;


switch (tp)
{
case 't'://RGB-HSI
for(i=0; i<(int)myPHeight; i++)
{
for (j=0; j<(int)myPWidth; j++)
{
R=GetRValue(myPArray[i*myPWidth+j]);
G=GetGValue(myPArray[i*myPWidth+j]);