Getting color image from bitmap while image is 16bppGrayscale

Question

Hi,

Problem No1. My own Related problem

I asked the next question here

Now the Problem No 2 is.

When i am trying to open 16 Bit (Monocrome ) images from their raw pixel data then i am getting Error. Because i am using PixelFormat.Format16bppGrayscale on creation of Bitmap like

Bitmap bmp = new Bitmap(Img_Width, Img_Height,PixelFormat.Format16bppGrayscale);

So googled and found Format16bppGrayscale not supported so i modifed my code like below.

 PixelFormat format = PixelFormat.Format16bppRgb565;
 Bitmap bmp = new Bitmap(Img_Width, Img_Height, format);
 Rectangle rect = new Rectangle(0, 0, Img_Width, Img_Height);
 BitmapData bmpData = bmp.LockBits(rect, ImageLockMode.ReadWrite, format);
 Marshal.Copy(rawPixel, 0, bmpData.Scan0, rawPixel.Length);
 bmp.UnlockBits(bmpData);

Amazing thing is that i am getting the image now because i change the pixelFormat. But problem is that My monocrome (Grayscale) image look in various color.

How can i get the original appearance. I tried several grayscale method but not successful Please give me some unsafe code. Thanks,

Answer 1

BobPowell's GDI+ FAQ has a bit about greyscale. The 16bpp in .Net just doesn't work. I have to do everything in 32bpp and resort to external tools for conversion. Luckily (?) I get to stick with TIFF images most of the time. Also, this thread might help.

Answer 2

You need to change the pallet to a greyscale pallet. The default pallet for 8bppIndexed is 256 colour. You can change it like this:

ColorPalette pal = myBitmap.Palette;

for (int i = 0; i < pal.Entries.Length; i++)
    pal.Entries[i] = Color.FromArgb(i, i, i);

myBitmap.Palette = pal;