Image Processing and Data

Digital image of a Galaxy
Credit: NSO

Astronomers take images with telescopes because they want to use them to do research in science. They need to be able to make measurements on these images. These could be the brightness of a star or the exact position of a planet.

This means that the images are not just pictures. They are huge amounts of data stored as an image. The data lists the number of photons (packets of light) collected by every single pixel on the telescopes' camera. These cameras are usually CCD detectors. Each data image can contain many millions of pixels.

This data is usually stored in special files called FITS files. These are the same no matter what telescope is used, anywhere in the world. The files are usually very large. A typical image data file from the Liverpool Telescope will have more than 4 million numbers in it! To deal with all these numbers astronomers use special computer programs called image analysis or processing software. These let us make the measurements we need.