Saving a cropped image

      I have code to upload and save a picture as a thumbnail.  The thumbnail code works great.  The problem is I'm trying to then crop the thumbnail to a square pixel of 55 by 55.    I'm using code that normally would be saving the image to a screen, but I'm saving the image as a file into a web directory.  The thumbnail saves as 55 x 55, but it is not being cropped.  It's just being squished to fit into  the 55 square.  Again, thumbnail code works great - I show some of it here just to show where I'm getting the image to work with to crop it.  Can someone look at my code starting at:
STARTING HERE FOR CROPPING THUMBNAIL IMAGE
and see if I'm either cropping wrong, or saving the cropped image wrong?   Thanks.


     code getting ready for thumbnail creation......

               Response.ContentType = "image/jpeg"
               'call the function to create the thumbnail
                thumb = Ettienne_Thumbnail(originalimg, height, width)
                'make the quality of thumbnail as good as possible
                Dim codecEncoder As ImageCodecInfo = GetEncoder("image/jpeg")
                Dim quality As Integer = 100
                Dim encodeParams As New EncoderParameters(1)
                Dim qualityParam As New EncoderParameter(Imaging.Encoder.Quality, quality)
                encodeParams.Param(0) = qualityParam
               
                thumbHeight = thumb.Height
                thumbWidth = thumb.Width

********  STARTING HERE FOR CROPPING THUMBNAIL IMAGE
                ' create a new bitmap that will be the end result for the cropped picture
                Dim bitthumb As New System.Drawing.Bitmap(55, 55, PixelFormat.Format24bppRgb)

                ' create a graphics object to work with
                Dim graphicthumb As Graphics = Graphics.FromImage(bitthumb)

                ' blank the image
                graphicthumb.Clear(Color.Blue)

                '# crop and resize!

                ' Set a unit of measurement as pixel
                ' could have used Inch, Point, etc
                Dim unit = GraphicsUnit.Pixel

                ' Draw image using the Pixel unit
                ' set above
                graphicthumb.DrawImage(thumb, New Rectangle(0, 0, 55, 55), New Rectangle(0, 0, thumbWidth, thumbHeight), unit)
               

                ' set the content type
                Response.ContentType = "image/jpeg"

                ' SAVE THE IMAGE USING THE ENCODE PARAMETERS
                bitthumb.Save(pathForThumb, codecEncoder, encodeParams)
                thumbHeight = bitthumb.Height
                thumbWidth = bitthumb.Width