How to Resize Images in C# While Maintaining Optimal Quality?

High-Quality Image Resizing in C#

Resizing images in C# often involves using the System.Drawing.Image class's Size, Width, and Height properties. However, a simple resizing approach can compromise image quality. For optimal results, employ a more sophisticated method like the one below:

public static Bitmap ResizeImage(Image image, int width, int height)
{
    var destRect = new Rectangle(0, 0, width, height);
    var destImage = new Bitmap(width, height);

    destImage.SetResolution(image.HorizontalResolution, image.VerticalResolution);

    using (var graphics = Graphics.FromImage(destImage))
    {
        graphics.CompositingMode = CompositingMode.SourceCopy;
        graphics.CompositingQuality = CompositingQuality.HighQuality;
        graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
        graphics.SmoothingMode = SmoothingMode.HighQuality;
        graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;

        using (var wrapMode = new ImageAttributes())
        {
            wrapMode.SetWrapMode(WrapMode.TileFlipXY);
            graphics.DrawImage(image, destRect, 0, 0, image.Width, image.Height, GraphicsUnit.Pixel, wrapMode);
        }
    }

    return destImage;
}

This method leverages several key features to ensure high-quality resizing:

• wrapMode.SetWrapMode(WrapMode.TileFlipXY): Eliminates artifacts (ghosting) at image edges by mirroring the image during the scaling process.
• destImage.SetResolution(...): Preserves the image's DPI (dots per inch), crucial for maintaining quality when reducing size or preparing for print.
• High-Quality Graphics Settings: CompositingQuality, InterpolationMode, SmoothingMode, and PixelOffsetMode are all set to HighQuality or HighQualityBicubic for superior rendering.

Important Considerations:

This function doesn't inherently manage aspect ratio; you'll need to handle that aspect yourself to prevent distortion. Furthermore, remember that saving the resized image (e.g., using destImage.Save(...)) can also impact quality. Consult external resources for best practices in image saving formats and compression levels.

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