opencv彩色图像灰度化的问题

#include "stdafx.h"
#include "cv.h"
#include "highgui.h"
/**************************最大值法灰度化****************************************/
IplImage * RGBtoGRAYTmax(IplImage *in,IplImage *out)
{ 
for (int y=0;y<in->height;y++)
{
uchar *ptr=(uchar*)(in->imageData+y*in->widthStep);
for (int x=0;x<in->width;x++)
{
if(ptr[3*x]>ptr[3*x+1])
out->imageData[y * in->width+ x]=ptr[3*x];
else out->imageData[y * in->width + x]=ptr[3*x+1];
if(ptr[3*x+2]>in->imageData[x])
out->imageData[y * in->width + x]=ptr[3*x+2];
}
}
return(out);
}
//*************************平均值法灰度化********************************
IplImage * AveGRAY(IplImage*in,IplImage*out)
{
for (int y=0;y<in->height;y++)
{
char *p=(char*)(in->imageData+y*in->widthStep);
for (int x=0;x<in->width;x++)
{
out->imageData[y*in->width+x]=(p[3*x]+p[3*x+1]+p[3*x+2])/3;
}