From ESRI:

A raster dataset contains one or more layers called bands. For example, a color image has three bands (red, green, and blue) while a digital elevation model (DEM) has one band (holding elevation values), and a multispectral image may have many bands.

Each raster band contains the actual cell values, as well as some key properties, such as:

  • Statistics: minimum, maximum, and mean cell values
  • Histogram of cell values
  • Default color map for raster display (optional)

Examples of a 1 band raster are

  • Elevation Data
  • Grayscale aerial imagery
  • Scanned maps/documents

Examples of 3 band raster are

  • Most color TIFFs, IMGS or MrSIDSs
  • Remotely Sensed/Spectral data
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