如何在使用图形 class 设置插值后保存 bitmap

Question

This code resizes an image and saves it to disk.

using (var medBitmap = new Bitmap(fullSizeImage, newImageW, newImageH))
{
     medBitmap.Save(HttpContext.Current.Server.MapPath("~/Media/Items/Images/" + itemId + ".jpg"),
                    ImageFormat.Jpeg);
}

But if I want to use the graphics class to set the interpolation, how do I save it? The graphics class has a save method, but it doesn't take any parameters. How do I save it to disk like the bitmap? Heres a modified code snippet:

using (var medBitmap = new Bitmap(fullSizeImage, newImageW, newImageH))
{
     var g = Graphics.FromImage(medBitmap);
     g.InterpolationMode = InterpolationMode.HighQualityBicubic;
     //What do I do now?
     medBitmap.Save(HttpContext.Current.Server.MapPath("~/Media/Items/Images/" + itemId + ".jpg"),
                    ImageFormat.Jpeg);
}

I just need to set the interpolation and then save it to disk.

Answer 1

Call DrawImage on the Graphics object to update the bitmap:

using (var medBitmap = new Bitmap(fullSizeImage, newImageW, newImageH))
{
  using (var g = Graphics.FromImage(medBitmap))
  {
    g.InterpolationMode = InterpolationMode.HighQualityBicubic;
    g.DrawImage(medBitmap, 0, 0);
  }
  medBitmap.Save(HttpContext.Current.Server.MapPath("~/Media/Items/Images/" + itemId + ".jpg"), ImageFormat.Jpeg);
}

Answer 2

Create a new Bitmap with the size you want and set the interpolationMode. Then use Graphics.DrawImage to draw the full sized image into the new bitmap.