convert 32bpp Bitmap to 16bpp (Grayscale)

Question

I'm creating a Bitmap in C# from an Image object.

The Bitmap I get is 32bpp, how can I transform that to 16bpp?

Bitmap image_bmp;
System.Drawing.Image tmp = (System.Drawing.Image)img.RenderImage(0); //RenderImage creates an object of tyoe System.Drawing.Image
image_bmp = new Bitmap(tmp);

16bpp ...grayscale? color? You'll need to be a bit more specific on what format you want! : ) — drew_w, Jun 20 '14 at 19:50

score 1 · Accepted Answer · edited May 23 '17 at 11:57

If you run a quick search on google you can find a number of excellent color to grayscale formulas. Take the following from wikipedia as an example:

Y' =  0.2126 R' + 0.7152 G' + 0.0722 B'

With this in mind the general process in .NET is going to be:

Create a new image of the correct dimensions with 16bpp grayscale
Use "LockBits" on the original image and the new image and loop over each pixel
Unlock both images, then save the new image to a file

Rather than going into these steps further I found a few other questions from stack and around the web that really delve into the details more. See:

Best of luck!

NOTE - I'm assuming your using GDI+. The steps are is similar for Windows Imaging Component (WIC) but the classes and syntax is radically different.

convert 32bpp Bitmap to 16bpp (Grayscale)

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