raw pixel array to gray scale BitmapImage

Question

I have an array of raw pixel data. I would like to convert it into 8bpp Bitmap.

public static Bitmap ByteToGrayBitmap(byte[] rawBytes, int width, int height) 
{ 
    Bitmap bitmap = new Bitmap(width, height, PixelFormat.Format8bppIndexed);
    BitmapData  bitmapData = bitmap.LockBits(new Rectangle(0, 0, width, height),
                                    ImageLockMode.WriteOnly, bitmap.PixelFormat);

    Marshal.Copy(rawBytes, 0, bitmapData .Scan0, rawBytes.Length);
    bitmap.UnlockBits(bitmapData);

    return bitmap;
}

bitmap looks like a color image instead of grayscale.

Answer 1

You need a 8-bit grayscale palette in your image.

Add this before you return:

var pal = bmp.Palette;
for (int i = 0; i < 256; i++) pal.Entries[i] = Color.FromArgb(i, i, i);
bmp.Palette = pal;

return bmp;

Answer 2

Try adding this before you return the bitmap:

for (int c = 0; c < bitmap.Palette.Entries.Length; c++)
    bitmap.Palette.Entries[c] = Color.FromArgb(c, c, c);

It will create a typical grayscale palette.