The numerical value of a specific pixel.

The value of a variable recorded for each pixel in an image; in the range of 0-255 for 8-bit data.

The gray level output from a digital camera (0-255 for an 8-bit system or 0-4095 for a 12-bit system).

A Digital Number or DN is the value stored within a pixel or cell of an image. Typically, the DN of the pixel represents the amount of light reflected back to the satellite/sensor. However, this is dependent upon the type of data stored in the image. For example, here is a list of some types of images and what the DN would represent: DEM, Elevation Sonar, Strength of returned soundwave Radar, Strength of returned microwave Thermal Infrared, Heat emission Regardless of what the DN represents, they are treated in the same way when displayed. That is, a DN of 0 will appear as black, of 127 will appear gray, and of 255 will appear white. The example image given below shows an image in which DN values progress from 0 to 255 from left to right.

A Value assigned to a pixel in a digital image. Also called counts.