Why does Image.GetThumbnailImage work differently on IIS6 and IIS7.5? - asp.net

Question

Bit of a strange question and I don't know whether anyone will have come across this one before.
We have a ASP.net page generating physical thumbnail jpeg files on a filesystem and copying fullsize images to a different location. So we input one image and we get a complete copy in one location and a small image 102*68 in a different location.
We're currently looking to finally move away from IIS6 on Server 2003 to IIS7.5 on Server 2008R2, except there's on problem.
On the old system (so IIS6/Server 2003) the black borders are removed and the image stays at the correct ration. On the new system (IIS7.5/Server 2008) the thumbnails are rendered exactly as they exist in the JPEG, with black borders, but this makes the thumbnail slightly squashed and obviously includes ugly black borders.
Anyone know why this might be happening? I've done a google and can't seem to find out which behaviour is "correct". My gut tells me that the new system is correctly rendering the thumbnail as it exists, but I don't know.
Anyone have any suggestions how to solve the problem?

Answer 1

I think as suggested it is the .net differences. not IIS.
Just re write your code, your save a lot of time, very simple thing to do.
Here is a image handler i wrote a while ago that re draws any image to your settings.
public class image_handler : IHttpHandler
{
public void ProcessRequest(HttpContext context)
{
// set file
string ImageToDraw = context.Request.QueryString["FilePath"];
ImageToDraw = context.Server.MapPath(ImageToDraw);
// Grab images to work on's true width and height
Image ImageFromFile = Image.FromFile(ImageToDraw);
double ImageFromFileWidth = ImageFromFile.Width;
double ImageFromFileHeight = ImageFromFile.Height;
ImageFromFile.Dispose();
// Get required width and work out new dimensions
double NewHeightRequired = 230;
if (context.Request.QueryString["imageHeight"] != null)
NewHeightRequired = Convert.ToDouble(context.Request.QueryString["imageHeight"]);
double DivTotal = (ImageFromFileHeight / NewHeightRequired);
double NewWidthValue = (ImageFromFileWidth / DivTotal);
double NewHeightVale = (ImageFromFileHeight / DivTotal);
NewWidthValue = ImageFromFileWidth / (ImageFromFileWidth / NewWidthValue);
NewHeightVale = ImageFromFileHeight / (ImageFromFileHeight / NewHeightVale);
// Set new width, height
int x = Convert.ToInt16(NewWidthValue);
int y = Convert.ToInt16(NewHeightVale);
Bitmap image = new Bitmap(x, y);
Graphics g = Graphics.FromImage(image);
Image thumbnail = Image.FromFile(ImageToDraw);
// Quality Control
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.SmoothingMode = SmoothingMode.HighQuality;
g.PixelOffsetMode = PixelOffsetMode.HighQuality;
g.CompositingQuality = CompositingQuality.HighQuality;
g.DrawImage(thumbnail, 0, 0, x, y);
g.Dispose();
image.Save(context.Response.OutputStream, ImageFormat.Jpeg);
image.Dispose();
}
public bool IsReusable
{
get
{
return true;
}
}