How can I get a 24bppRgb screen shot?

A few days ago I set about trying to accomplish (what I thought would be) a simple task, namely to find an image that could be located anywhere in the screen (not within my winform application) using Emug CV rather than Aforge.

Bitmap sShot = new Bitmap(Screen.PrimaryScreen.Bounds.Width,
                                  Screen.PrimaryScreen.Bounds.Height,
                                  PixelFormat.Format24bppRgb);

Creates a 24bbpRgb image as required....

// Create a graphics object from the bitmap.
Graphics gfxScreenshot = Graphics.FromImage(sShot);

// Take the screenshot from the upper left corner to the right bottom corner.
gfxScreenshot.CopyFromScreen(Screen.PrimaryScreen.Bounds.X, Screen.PrimaryScreen.Bounds.Y,
                             0, 0,
                             Screen.PrimaryScreen.Bounds.Size,
                             CopyPixelOperation.SourceCopy);

The image is now a 32bppArgb (I assume, photoshop won't load it)

// Process the image from whatever format it starts in to 24bppRgb (hopefully)

private Bitmap convert24RGB(Image sourceImage)
{
    int loopX, loopY = 0;
    Bitmap sourceBMP, processedBMP;
    System.Drawing.Color myPixel;

    int myHeight = sourceImage.Size.Height;
    int myWidth = sourceImage.Size.Width;

    sourceBMP = new Bitmap(sourceImage);
    processedBMP = new Bitmap(myWidth, myHeight, System.Drawing.Imaging.PixelFormat.Format24bppRgb);

    // ----- This was just to make sure the image created actually was 24bpp
    using (Graphics g = Graphics.FromImage(processedBMP))
    {
        g.FillRectangle(new SolidBrush(Color.Blue), 0, 0, myWidth-1, myHeight-1);
    }
    processedBMP.Save("blue24bpp");
    // ------

    for (loopY = 0; loopY < myHeight; loopY++)
        for (loopX = 0; loopX < myWidth; loopX++)
        {
            myPixel = sourceBMP.GetPixel(loopX, loopY);
            processedBMP.SetPixel(loopX, loopY, myPixel);
        }
    return processedBMP;
}

This is just the latest of maybe a dozen methods I have tried and yet again it got converted to 32bppArgb.

I would love to discover I have overlooked something extremely simple but it's driving me insane!