An System.Drawing.Image stores a value for pixel width and a value for horizontal resolution (dots per inch). The physical width, measured in inches, of an image is the pixel width divided by the horizontal resolution. For example, an image with a pixel width of 216 and a horizontal resolution of 72 dots per inch has a physical width of 3 inches. Similar remarks apply to pixel height and physical height.

The Graphics.DrawImageUnscaled(Image, int, int) method draws an image using its physical size, so the image will have its correct size in inches regardless of the resolution (dots per inch) of the display device. For example, suppose an image has a pixel width of 216 and a horizontal resolution of 72 dots per inch. If you call Graphics.DrawImageUnscaled(Image, int, int) to draw that image on a device that has a resolution of 96 dots per inch, the pixel width of the rendered image will be (216/72)*96 = 288.

Namespace: System.Drawing
Assembly: System.Drawing (in System.Drawing.dll)
Assembly Versions: 1.0.5000.0, 2.0.0.0