how to get Bitsperpixel from a bitmap

Question

I have a 3rd party component which requires me to give it the bitsperpixel from a bitmap.

What's the best way to get "bits per pixel"?

My starting point is the following blank method:-

public int GetBitsPerPixelMethod( system.drawing.bitmap bitmap )
{
   //return BitsPerPixel;
}

Answer 1

var source = new BitmapImage(new System.Uri(pathToImageFile));
int bitsPerPixel = source.Format.BitsPerPixel;

The code above requires at least .NET 3.0

http://msdn.microsoft.com/en-us/library/system.windows.media.imaging.bitmapimage.aspx

Answer 2

What about Image.GetPixelFormatSize()?

Answer 3

Try:

Bitmap.PixelFormat

See possible values of the PixelFormat property.

Answer 4

The Bitmap.PixelFormat property will tell you the type of pixel format that the bitmap has, and from that you can infer the number of bits per pixel. I'm not sure if there's a better way of getting this, but the naive way at least would be something like this:

var bitsPerPixel = new Dictionary<PixelFormat,int>() {
    { PixelFormat.Format1bppIndexed, 1 },
    { PixelFormat.Format4bppIndexed, 4 },
    { PixelFormat.Format8bppIndexed, 8 },
    { PixelFormat.Format16bppRgb565, 16 }
    /* etc. */
};

return bitsPerPixel[bitmap.PixelFormat];

Answer 5

Use the Pixelformat property, this returns a Pixelformat enumeration which can have values like f.e. Format24bppRgb, which obviously is 24 bits per pixel, so you should be able to do something like this:

switch(Pixelformat)       
  {
     ...
     case Format8bppIndexed:
        BitsPerPixel = 8;
        break;
     case Format24bppRgb:
        BitsPerPixel = 24;
        break;
     case Format32bppArgb:
     case Format32bppPArgb:
     ...
        BitsPerPixel = 32;
        break;
     default:
        BitsPerPixel = 0;
        break;      
 }

Answer 6

Rather than creating your own function, I'd suggest using this existing function in the framework:

Image.GetPixelFormatSize(bitmap.PixelFormat)