How to resize an Image C#

Question

As Size, Width and Height are Get() properties of System.Drawing.Image;
How can I resize an Image object at run-time in C#?

Right now, I am just creating a new Image using:

// objImage is the original Image Bitmap objBitmap = new Bitmap(objImage, new Size(227, 171)); 

Answer 1

This will perform a high quality resize:

/// <summary> /// Resize the image to the specified width and height. /// </summary> /// <param name="image">The image to resize.</param> /// <param name="width">The width to resize to.</param> /// <param name="height">The height to resize to.</param> /// <returns>The resized image.</returns> 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; } 

• wrapMode.SetWrapMode(WrapMode.TileFlipXY) prevents ghosting around the image borders -- naïve resizing will sample transparent pixels beyond the image boundaries, but by mirroring the image we can get a better sample (this setting is very noticeable)
• destImage.SetResolution maintains DPI regardless of physical size -- may increase quality when reducing image dimensions or when printing
• Compositing controls how pixels are blended with the background -- might not be needed since we're only drawing one thing.
  • graphics.CompositingMode determines whether pixels from a source image overwrite or are combined with background pixels. SourceCopy specifies that when a color is rendered, it overwrites the background color.
  • graphics.CompositingQuality determines the rendering quality level of layered images.
• graphics.InterpolationMode determines how intermediate values between two endpoints are calculated
• graphics.SmoothingMode specifies whether lines, curves, and the edges of filled areas use smoothing (also called antialiasing) -- probably only works on vectors
• graphics.PixelOffsetMode affects rendering quality when drawing the new image

Maintaining aspect ratio is left as an exercise for the reader (actually, I just don't think it's this function's job to do that for you).

Also, this is a good article describing some of the pitfalls with image resizing. The above function will cover most of them, but you still have to worry about saving.

Answer 2

Not sure what is so difficult about this, do what you were doing, use the overloaded Bitmap constructor to create a re-sized image, the only thing you were missing was a cast back to the Image data type:

public static Image resizeImage(Image imgToResize, Size size) {     return (Image)(new Bitmap(imgToResize, size)); }  yourImage = resizeImage(yourImage, new Size(50,50));