Mumbai university > Electronics and telecommunication Engineering > Sem 6 > Television Engineering

Marks: 05

Years: May 2016

Luminance:

• This is the amount of light intensity as perceived by the eye regardless of the colour.

• In black and white pictures, better lighted parts have more luminance than the dark areas.

• Different colours also have shades of luminance in the sense that though equally illuminated appear more or less bright as indicated by the relative brightness response curve shown below.

• Thus on a monochrome TV screen, dark red colour will appear as black, yellow as white and a light blue colour as grey.

Hue:

• This is the predominant spectral colour of the received light.

• Thus the colour of any object is distinguished by its hue or tint.

• The green leaves have green hue and red tomatoes have red hue.

• Different hues result from different wavelengths of spectral radiation and are perceived as such by the sets of cones in the retina.

Saturation:

• This is the spectral purity of the colour light.

• Since single hue colours occur rarely alone, this indicates the amounts of other colours present.

• Thus saturation may be taken as an indication of how little the colour is diluted by white.

• A fully saturated colour has no white.

• As an example, vivid green is fully saturated and when diluted by white, it becomes light green.

• The hue and saturation of a colour put together is known as chrominance. It does not contain the brightness information. Chrominance is also called Chroma.