Can Graphics.DrawImage unintentionally trim an image?

Question

I'm using code that takes a bitmap and converts it to 24 BPP so that I can use it in a program that specifically requires that file format. Here is the code:

    using (Bitmap tempImage = new Bitmap(pageToScan.FullPath))
    {
    if (tempImage.PixelFormat != System.Drawing.Imaging.PixelFormat.Format24bppRgb)
    {
    using (Bitmap tempImage2 = new Bitmap(tempImage.Size.Width, tempImage.Size.Height,
    System.Drawing.Imaging.PixelFormat.Format24bppRgb))
    {
    using (Graphics g = Graphics.FromImage(tempImage2))
    {
    g.DrawImage(tempImage, new Point(0, 0));
    }
    RecognizeBitmap(pageToScan, tempImage2); //Thanks to Tim on this refactoring.
    }
    }
    else
    RecognizeBitmap(pageToScan, tempImage);
    }

I have two questions about the code above:

1. With a particular image, I think that this clipped the rightmost 200 pixels right off of tempImage2. Is this possible? How might this happen, and how can I stop it? A friend of mine suggested that it might have to do with the stride of the TIFF file being used.
2. Is there a faster way to convert an image to 24 BPP in memory?

Answer 1

A better way is to use the Bitmap.Clone method. This takes a PixelFormat as a parameter:

using (Bitmap tempImage = new Bitmap(pageToScan.FullPath))    
{           
    if (tempImage.PixelFormat != System.Drawing.Imaging.PixelFormat.Format24bppRgb)
    {
        Rectangle r = new Rectangle(0, 0, tempImage.Width, tempImage.Height);
        RecognizeBitmap(pageToScan, tempImage.Clone(r, PixelFormat.Format24bppRgb);          
    }
    else                  
    {
        RecognizeBitmap(pageToScan, tempImage);    
    }
}