Why are some satellite images in black and white and others in colour?
Some sensors record images from just one part of the electromagnetic spectrum, showing the image in shades (usually 256) of grey making what’s called a “black and white” image. This is how RADARSAT works. When an image is recorded simultaneously in several parts of the spectrum, then three of those spectral “bands” are shown as shades of red and green and blue. Landsat and SPOT images are often displayed this way. From those three primary additive colours, one can make any of the other colours such as orange, brown, turquoise, etc. That is also how your TV and your computer monitor work – when the three images in red, green and blue are superimposed on the screen, a full range of colour results.
