Raster, pixel, dn , band

Raster data is like a big picture made up of small squares called pixels. Each pixel shows some information about a small part of the Earth's surface, like how hot, bright, or green that spot is.

Pixels

Pixels are the tiny squares in a raster image. Just like how your phone screen is made of pixels, a satellite image also has pixels. Each pixel tells us something about the place it covers.

DN Values (Digital Numbers)

Each pixel has a number inside it, called a DN value.
This number tells us what's going on in that area — for example:

A high number might mean a bright area,
A low number might mean a dark area.
It can also show things like temperature, elevation, or vegetation.

Bands

Some satellite images have one band (like black-and-white photos).
Others have many bands, each showing a different kind of light:

Red, green, and blue (like what we see with our eyes),
Near-infrared (helps us see plants and vegetation),
Thermal (shows heat).

Each band gives different information to help us understand the Earth's surface better.

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History of Geography.

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Vineesh V, Geography

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