Extracting a portion of Image in C# - c#-4.0

Question

I have made a C# Windows application with two Picture-Boxes one as MainPictureBox and other as ThumbnailBox, I want to Extract a portion of Image upon moving mouse over Main Image and load it into ThumbnailPictureBox.

Answer 1

Here is a way to get a thumbnail from the image.
public static Bitmap Thumb(this Image inputStream, int width, int height)
{
using (var bitMap = new Bitmap(inputStream))
{
int originalWidth = bitMap.Width;
int originalHeight = bitMap.Height;
int startPositionHeight = 0;
int startPosionWidth = 0;
int widthHeight = 0;
if (originalWidth > originalHeight)
{
startPosionWidth = (originalWidth - originalHeight) / 2;
widthHeight = originalHeight;
}
else if (originalHeight > originalWidth)
{
startPositionHeight = (originalHeight - originalWidth) / 2;
widthHeight = originalWidth;
}
else if (originalWidth == originalHeight)
{
widthHeight = originalHeight;
}
var rect = new Rectangle(startPosionWidth, startPositionHeight, widthHeight, widthHeight);
using (Bitmap cropped = bitMap.Clone(rect, bitMap.PixelFormat))
{
using (var newbitmap = new Bitmap(cropped, width, height))
{
var stream = new MemoryStream();
newbitmap.Save(stream, ImageFormat.Tiff);
stream.Position = 0;
return new Bitmap(stream);
}
}
}
}