> For the complete documentation index, see [llms.txt](https://guides.geospatial.bas.ac.uk/10-things-to-know-about-vhr-satellite-data/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://guides.geospatial.bas.ac.uk/10-things-to-know-about-vhr-satellite-data/6.-radiometric-resolution-and-correction.md).

# 6. Radiometric resolution and correction

#### Radiometric resolution

The radiometric resolution refers to how much information is contained within the image – effectively what the bit-depth is. ​

An image may be 8 bit, 16 bit or 32 bit. ​

#### Radiometric correction

The radiometric correction is the process of correcting the colour and brightness of the image to take out spectral distortion. ​

When light passes through the atmosphere some wavelengths are absorbed or reflected more than others. ​

There are two main types of correction for this: ​

1. Top Of Atmosphere (TOA) correction; based on the known position and angle of the satellite and the sensor
2. Full Atmospheric Correction (FAC); based on knowing the composition of the atmosphere at the time of the image.​

​Getting a true FAC is usually difficult in Antarctica, as we rarely know the composition of the atmosphere. But luckily, the levels of aerosols and other pollutants are small, so usually a TOC correction will suffice.