Manipulate a System.Drawing.Image and save with same ImageFormat

Question

Let's say I want a method that does some manipulation on an image by messing with its pixel values and then returns an image which is otherwise the "same" (equal PixelFormat, RawFormat, VerticalResolution, etc.).

public static Image DoSomeManipulation(this Image source)
{
    // ... 
}

I've been finding this remarkably difficult to do because to manipulate its pixels I want to use Bitmap and I can't find a way to create a Bitmap which has the same ImageFormat.

I've tried:

var target = new Bitmap(source);

and

var temp = new Bitmap(source)
var target = temp.Clone(new Rectangle(0, 0, temp.Width, temp.Height), source.PixelFormat);

and

var temp = new Bitmap(source)
var target = temp.Clone(new Rectangle(0, 0, temp.Width, temp.Height), temp.PixelFormat);

and while each of them works some of the time for my test on my 1,000 random files (PNGs, JPGs, etc.), all of them fail

Assert.AreEqual(target.ImageFormat, source.ImageFormat);

some of the time and I can't figure out why that is.

Is there any solution that doesn't involve one of

• Serializing and deserializing source (Yes, I've seen this)
• If source is a local file, creating copy in Temp storage or something like that

??