Pixel
Overview
Pixel is the smallest unit of a raster image in GIS, representing a specific area on the ground with a single value, such as color or elevation. The term is a contraction of “picture element” and forms the building blocks of all raster data.
Key Concepts
Cell size is the ground dimension of a pixel (e.g., 30m x 30m). Resolution is the pixel size; smaller pixels = higher resolution. Bit depth is the number of bits used to store pixel values (8-bit = 256 values). Band is a single layer of values (RGB images have 3 bands). NoData is a special value indicating no valid data for a pixel.
Pixel Values
| Data Type | Bit Depth | Value Range |
|---|---|---|
| Unsigned 8-bit | 8 | 0 to 255 |
| Signed 16-bit | 16 | -32,768 to 32,767 |
| Unsigned 16-bit | 16 | 0 to 65,535 |
| 32-bit float | 32 | Continuous decimal |
Appendix
Created: 2025-12-13 | Modified: 2025-12-13