Why are space images typically black and white?
1 Answer
Monochrome images require far less information to re-produce after the image has been acquired, then transmitted, received and computed. Newer, recent images will have more colour.
Explanation:
How are the Hubble images in the image archive created?
Like any modern telescope, Hubble captures images on a digital device that transforms photons into electrons; and the latter carry no colour information. However, filters placed in front of the camera only allow for specific kinds of light (blue or green light, infrared light or ultraviolet radiation) to pass through them and into the camera.
Therefore, most of the images found on spacetelescope.org are actually a combination of several identical images, each taken through a different filter. To create the final image, these individual images are coloured — depending on the type of light they represent — and then combined with the others.
We colour the images as accurately as possible to correspond with the filters, but sometimes this is not entirely possible. For example, we can not accurately represent those colours invisible to the human eye, such as infrared and ultraviolet light. Therefore, in this case, the filters are represented by colours we can see — though the final image does not represent what the human eye would see if it looked upon the subject in the night sky.
Data from Hubble is also contaminated with defects, such as bright pixels — caused by high-energetic particles — and dead pixels, which no longer collect light and noise. These defects are removed to create those images released to the public.
