Bands

Images are generally made up of data in a 2D array. For our purposes we'll imagine that each data value is a pixel in an image (that is, a dot on a screen). Often images will have different bands: different sets of figures that come together to give a colour to a pixel. For example, we might have a band in a satellite image that is the data from its near-infrared sensor and another band that is from its radar sensor and another from its green intensity sensor. Each band will have its own 2D array of values.

Any given pixel is made up of different levels of red, green, and blue light from the screen. We might assign the near-infrared to the red level, the radar to the blue level, and the green intensity to the green level. In combination the levels of the three different colours, set by the level of the data for each band, will give a particular colour.