3 channel depth image 1 channel

Question

I have record a depth video using Kinect v2, when I extracted images using MATLAB then each image is 3 channel. Normally the images I saw are just 1 channel. Please any one tell me how can make this 3 channel image to 1 channel?

Here is the code of the depth part:

IplImage depth = new IplImage(512, 424, BitDepth.U16, 1);
CvVideoWriter DepthWriter;
Width = sensor.DepthFrameSource.FrameDescription.Width;
DHeight = sensor.DepthFrameSource.FrameDescription.Height;
WbDepth = new WriteableBitmap(DWidth, DHeight, 96, 96, PixelFormats.Gray16, null);
int depthshft = (int)SliderDepth.Value;
using (DepthFrame depthframe = frame.DepthFrameReference.AcquireFrame())
ushort* depthdata = (ushort*)depth.ImageData;
if (depthframe != null)
   {
    Depthdata = new ushort[DWidth * DHeight];
    ushort[] Depthloc = new ushort[DWidth * DHeight];
    depthframe.CopyFrameDataToArray(Depthdata);
    for (int i = 0; i < DWidth * DHeight; i++)
        {
          Depthloc[i] = 0x1000;
        }
        colorspacePoint = new ColorSpacePoint[DWidth * DHeight];
        depthspacePoint = new DepthSpacePoint[CWidth * CHeight];
        sensor.CoordinateMapper.MapDepthFrameToColorSpace(Depthloc, colorspacePoint);
        for (int y = 0; y < DHeight; y++)
            {
            for (int x = 0; x < DWidth; x++)
                {
                if (depthshft != 0)
                   {
                    Depthdata[y * DWidth + x] = (ushort)((Depthdata[y * DWidth + x]) << depthshft);
                   }

                 }
             }
         depth.CopyPixelData(Depthdata);
 }
WbDepth.WritePixels(new Int32Rect(0, 0, DWidth, DHeight), Depthdata, strideDep, 0);
ImageDepth.Source = WbDepth;
if (depth != null && DepthWriter.FileName != null) Cv.WriteFrame(DepthWriter, depth);
Cv.ReleaseVideoWriter(DepthWriter);
if (CheckBox_saveD.IsChecked == true)
DepthWriter = new CvVideoWriter(string.Format("{1}\\Scene{0}_DepthRecord.avi", scene, TextBlock_saveloca.Text.ToString()), FourCC.Default, 30.0f, new CvSize(512, 424));
CheckBox_saveD.IsEnabled = false;
if (CheckBox_saveD.IsChecked == true) Cv.ReleaseVideoWriter(DepthWriter);

Thank you

Answer 1

Everyone so far is advising you to convert the (supposedly) color image to grayscale. I don't think you should do this. The kinect gives you a "1 channel" image of depth values. If you have a color (3 channel) depth map, then something is wrong. Converting to gray scale will then make you lose depth information.

Instead, try to figure out why your image is loaded as gray scale in the first place. What is the source? Is the conversion maybe done by Matlab when reading the image? Can you then give it some flag to tell it not to?