How can I copy the pixel data from a Bitmap with negative stride?

Question

I was looking for the fastest way to convert a Bitmap to 8bpp. I found 2 ways:

1.

        public static System.Drawing.Image Conver         


        

Answer 1

I don't know why there is something strange about the Bitmap created by the FromHbitmap method, but I do know that you can fix it by using Bitmap bmpClone = (Bitmap)bmp.Clone(); and doing the LockBits on bmpClone.

Also, I found that if you use bmp.Clone(), you cannot Dispose() of bmp until you have finished with the clone.

This also works and let's you dispose of the negative stride image sooner rather than later:

        Bitmap bmp = null;
        using (Bitmap bmpT = CopyToBpp(bmpO, 1))
        {
            bmp = new Bitmap(bmpT);
        }