Colour in AstroPhotography

All photo-sensors are basically Black or White.
What you see in the Hubble Photographs too is Assigned Colour or False Colour.
Blue is Oxygen
Green Hydrogen 
Red is Sulphur

Blue Added

Red (Blue and Green )

See this NGC Video from 11min 15sec ( https://www.youtube.com/watch?feature=player_detailpage&list=WL&v=qcfN_HN4TVg#t=668 )
Hubble Docu

from 11mins or 668 seconds in the film Colour has a totally different use in Astronomy ie. Spectroscopy, which is putting a Prism, that Splits the light into in component colours of the Rainbow or VIBGYOR, in front of a "Camera Lens" (Camera-Lens here means any Photo sensitive material,  more like Xray than Polaroid) The Split Colours in the Rainbow Pattern is called SPECTRUM or SPECTRA(singular) that come out from the prism are recorded in Bar Code like Stripes (I think to remove any ambiguity about people perceiving colours differently). Using this we can find out what Element-chemical is emitting the light or aptly Radiating "Light"