.NET High Quality Thumbnail Generation

This method is a modified version of Mike Borozdin method which I happen to enjoy very much. The biggest changes I made where to add using statements around the disposable objects such as the Bitmap and the Graphics object to avoid memory leaks, as well as a few minor changes.

//Image Resize Helper Method
private static Bitmap ResizeImage(String filename, int maxWidth, int maxHeight)
    using (Image originalImage = Image.FromFile(filename))
        //Caluate new Size
        int newWidth = originalImage.Width;
        int newHeight = originalImage.Height;
        double aspectRatio = (double)originalImage.Width / (double)originalImage.Height;

        if (aspectRatio <= 1 && originalImage.Width > maxWidth)
            newWidth = maxWidth;
            newHeight = (int)Math.Round(newWidth / aspectRatio);
        else if (aspectRatio > 1 && originalImage.Height > maxHeight)
            newHeight = maxHeight;
            newWidth = (int)Math.Round(newHeight * aspectRatio);

        Bitmap newImage = new Bitmap(newWidth, newHeight);

        using (Graphics g = Graphics.FromImage(newImage))
            //--Quality Settings Adjust to fit your application
            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBilinear;
            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
            g.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality;
            g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
            g.DrawImage(originalImage, 0, 0, newImage.Width, newImage.Height);
            return newImage;
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1 comment

  1. Thanks – very practical. And, nice and compact compared to other examples which are perhaps overinvolved (download a whole project source code, etc).

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