16 bit raw to 24 bit depth colored image using C#

not camera data just ushort 16bit data, raw data: 512*512 16 bit ushort data just it. Like this in link.

data is 16bit

this code return gray scale 24 bit depth image:
private void CreateBitmap()
{
bmp = new Bitmap(width, height, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
BitmapData bmd = bmp.LockBits(new Rectangle(0, 0, width, height),
System.Drawing.Imaging.ImageLockMode.ReadOnly, bmp.PixelFormat);

// This 'unsafe' part of the code populates the bitmap bmp with data stored in pixel16.
// It does so using pointers, and therefore the need for 'unsafe'.
unsafe
{
int pixelSize = 3;
int i, j, j1, i1;
byte b;
ushort sVal;
double lPixval;

for (i = 0; i < bmd.Height; ++i)
{
byte* row = (byte*)bmd.Scan0 + (i * bmd.Stride);
i1 = i * bmd.Height;

for (j = 0; j < bmd.Width; ++j)
{
sVal = (ushort)(pixels16[i1 + j]);
lPixval = (sVal / 255.0); // Convert to a 255 value range
if( lPixval > 255 ) lPixval = 255;
if( lPixval < 0 ) lPixval = 0;
b = (byte)(lPixval);
j1 = j * pixelSize;
row[j1] = b; // Red
row[j1 + 1] = b; // Green
row[j1 + 2] = b; // Blue
}
}
}
bmp.UnlockBits(bmd);
}