Kinect depth Segmentation frame rate - c++

Question

I am new to kinect project
And I am implementing a depth threshold when distance is greater than 400mm
for (UINT y = 0; y < pImg->rows; ++y)
{
// Get row pointers for Mats
const USHORT* pDepthRow = depth->ptr<USHORT>(y);
for (UINT x = 0; x < pImg->cols; ++x)
{
USHORT raw_depth = pDepthRow[x];
SHORT realDepth = NuiDepthPixelToDepth(raw_depth);
// If depth value is valid, convert and copy it
if (raw_depth != 65535)
{
if(realDepth >400 ) //greater than 400mm
{
pImg->at<Vec4b>(y,x)[0] = 255;
pImg->at<Vec4b>(y,x)[1] = 255;
pImg->at<Vec4b>(y,x)[2] = 255;
pImg->at<Vec4b>(y,x)[3] = 255;
}
else
{
pImg->at<Vec4b>(y,x)[0] = 0;
pImg->at<Vec4b>(y,x)[1] = 0;
pImg->at<Vec4b>(y,x)[2] = 0;
pImg->at<Vec4b>(y,x)[3] = 0;
}
}
}
It seems get the correct result but reduces the frame rate massively.
When I want to get rid of the loop by using the cv::inRange, but this function only support 8U1C when the raw depth is 16U.
So what else can I use to segment the depth according to the real distance?

Answer 1

Try to improve performance by storing a reference to the pixel.
Change this:
if (realDepth > 400) //greater than 400mm
{
pImg->at<Vec4b>(y,x)[0] = 255;
pImg->at<Vec4b>(y,x)[1] = 255;
pImg->at<Vec4b>(y,x)[2] = 255;
pImg->at<Vec4b>(y,x)[3] = 255;
}
else
{
pImg->at<Vec4b>(y,x)[0] = 0;
pImg->at<Vec4b>(y,x)[1] = 0;
pImg->at<Vec4b>(y,x)[2] = 0;
pImg->at<Vec4b>(y,x)[3] = 0;
}
To this:
(I don´t know what T is because I dont know what pImg is.
T should be equal to the return value of the at method. I assume it is Vec4b.)
T& pixel = pImg->at<Vec4b>(y, x); // probably Vec4b& pixel = ..
if (realDepth > 400) //greater than 400mm
{
pixel[0] = 255;
pixel[1] = 255;
pixel[2] = 255;
pixel[3] = 255;
}
else
{
pixel[0] = 0;
pixel[1] = 0;
pixel[2] = 0;
pixel[3] = 0;
}