64-bit image color declaring (16 bit per channel)

Question

In C# I can declare new 48bitRGB or 64bitRGBA without problem, and in fact the right format is saved on disk.

However, when it comes to declaring a color, I am not able to declare color of more than 8-bit values. That seems to be because Color declarations expect no more than 8 bits per component.

The code I have so far:

int x;
int y;
int w = 512, h = 512;

Bitmap image = new Bitmap(w, h, System.Drawing.Imaging.PixelFormat.Format48bppRgb); //New image with 16bit per channel, no problem

// Double 'for' control structure to go pixel by pixel on the whole image
for (y = 0; y < h; y++)
{
    for (x = 0; x < w; x++)
    {
        comp = somevalue; //Numeric component value
        // Lo que vaya por aqui
        System.Drawing.Color newColor = System.Drawing.Color.FromArgb(255, comp, comp, comp); // <= Here is the problem, values can't exceed 256 levels
        image.SetPixel(x, y, newColor);
    }
}

image.Save(@"C:\test.png", System.Drawing.Imaging.ImageFormat.Png); //Saving image to disk

What is a method for declaring a 16-bit color component in C#?

Answer 1

The problem stems from the fact that the Bitmap class encapsulates a GDI+ bimap.

GDI+ version 1.0 and 1.1 can read 16-bits-per-channel images, but such images are converted to an 8-bits-per-channel format for processing, displaying, and saving. link

So when you are setting the value of the pixels you are dealing with the 8 bit per channel format.

If use use unsafe code you can access the values directly, see Get 64bpp image color.