Deep View of the Large and Small Magellanic Clouds

LRGB, short for

Luminance Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through, is emitted from, or is reflected from a particular area, and falls withi ...

Red Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–740 nanometres. It is a primary color in the RGB color model and a secondar ...

Green Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 Nanometre, nm. In subtractive color systems, used in painting and color printing, it is created by ...

and

Blue Blue is one of the three primary colours in the RYB colour model (traditional colour theory), as well as in the RGB (additive) colour model. It lies between violet and cyan on the spectrum of visible light. The eye perceives blue when obs ...

, is a photographic technique used in

amateur astronomy Amateur astronomy is a hobby where participants enjoy observing or imaging celestial objects in the sky using the unaided eye, binoculars, or telescopes. Even though scientific research may not be their primary goal, some amateur astronomers m ...

for producing good quality color photographs by combining a high-quality black-and-white image with a lower-quality color image.A Simple Guide to the LRGB Technique
In amateur

astronomy Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest ...

, it is easier and cheaper to obtain good quality, high

signal-to-noise ratio Signal-to-noise ratio (SNR or S/N) is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. SNR is defined as the ratio of signal power to the noise power, often expressed in deci ...

images in black and white. The LRGB method is used to work around this to get good color images. The color information from the color image is combined with the overall brightness from the black-and-white image. The theory behind the effectiveness behind LRGB techniques has been related to the working of human

color vision Color vision, a feature of visual perception, is an ability to perceive differences between light composed of different wavelengths (i.e., different spectral power distributions) independently of light intensity. Color perception is a part of ...

. The

rod cell Rod cells are photoreceptor cells in the retina of the eye that can function in lower light better than the other type of visual photoreceptor, cone cells. Rods are usually found concentrated at the outer edges of the retina and are used in per ...

s in human eyes are sensitive to luminance and spatial data, while the

cone cell Cone cells, or cones, are photoreceptor cells in the retinas of vertebrate eyes including the human eye. They respond differently to light of different wavelengths, and the combination of their responses is responsible for color vision. Cone ...

s are sensitive to color. There are three types of cones: those sensitive to red, those sensitive to green, and those sensitive to blue. Thus, each element of LRGB targets one type of

photoreceptor cell A photoreceptor cell is a specialized type of neuroepithelial cell found in the retina that is capable of visual phototransduction. The great biological importance of photoreceptors is that they convert light (visible electromagnetic radiatio ...

in the human eye.

References

Amateur astronomy Astrophotography {{astronomy-stub

See also

References