Gamma correction circuit for television
AssigneeU.S. Philips Corporation
InventorHendrik Blom
Life of this patent
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Abstract
A television gamma correction circuit in which a gamma corrector supplies an output signal having a minimum gamma equal to two, from which, relative to a linear input signal which is limited via a signal limiter circuit to the peak-white value, a correction signal is derived, with positive values only intended for increasing the gamma of the output signal of the gamma corrector. In this way scene details produced when the peak-white value is exceeded are prevented from being displayed with a lower picture brightness than associated with the peak-white value.
Claims7
A gamma correction circuit for television having an input, to which a signal to be gamma corrected is applied, and an output, wherein said gamma correction circuit comprises a gamma corrector coupled to said circuit input;
- a signal limiter also coupled to said circuit input;
- a first superposition stage, for forming a correction signal having a first and a second input and an output, said first input thereof being coupled to said gamma corrector and said second input thereof being coupled to said signal limiter circuit;
- and a second superposition stage having a first and a second input and an output, said first input thereof being coupled to the output of said first superposition stage and said second input thereof being coupled to said gamma corrector, said output thereof corresponding to said gamma correction circuit output, whereby the gamma-corrected output signal is formed by combining in said second superposition stage the output from said gamma corrector, having a minimum gamma, and the gamma-increasing correction signal at the output of said first superposition stage.
Dependencies are inferred from the claim text.