Human visual system model: Difference between revisions

Revision as of 05:53, 13 February 2008

Revision as of 06:00, 13 February 2008

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It is common to think of "taking advantage" of the HVS to produce desired effects. Examples of taking advantage of the HVS include colour television. Originally it was thought that colour television required too high a bandwidth for the then available technology. Then it was [[Chroma subsampling | noticed that the colour resolution of the HVS was much lower than the brightness resolution]]; this allowed colour to be squeezed into the signal. Another example is image compression, like [[JPEG]]. Our HVS model says that we cannot see high frequency detail so in JPEG we can quantise these components without a perceptible loss of quality. Similar concepts are applied in [[Audio_data_compression#Lossy_audio_compression | audio compression]], where sound frequencies inaudible to humans are bandpass filtered.

Several HVS features are derived from avatismsevolution, throwbacks to nature when we needed to defend ourselves or hunt for food. We often see demonstrations of HVS features when we are looking at optical illusions.

==Assumptions about the HVS==

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* Lack of colour resolution (less cones in human eye than rods)

* Motion sensitivity

** More sensitive atin periphery of[[peripheral vision]]

** Stronger than texture sensitivity, e.g. viewing a camouflaged animal

* Texture stronger that disparity - 3D depth resolution does not need to be so accurate

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{{reflist}}

[[Category: Image processing | Computer vision]]