Patent ID: 7038721

Claim:
A gamma correction circuit for correcting a digital video signal, the circuit comprising: a first lookup table ( 6 ) and a second lookup table ( 8 ) for storing discrete output intensity data and the associated slope data of a non-linear transfer function, respectively, for each of the discrete input video signal intensities, an adder ( 10 ) having a first input connected to the output of the first lookup table ( 6 ), a multiplier ( 12 ) having a first input connected to the output of the second look-up table ( 8 ), characterized by a quantizer ( 4 ) for providing the most significant bits of the incoming video signal to address the first and second lookup tables ( 6 , 8 ) and to transfer the corresponding output intensity data to the adder ( 10 ) and the associated slope data to the multiplier ( 12 ), the quantizer ( 4 ) transmitting the remaining least significant bits of the input video signal to the second input of the multiplier ( 12 ), the multiplier ( 12 ) multiplying the slope data with the remaining least significant bits and feeding the multiplication result to the second input of the adder ( 10 ), the adder ( 10 ) adding the output intensity data and the multiplication result to generate a corrected video signal; the input video path being n bits wide, the internal path being (q+p) bits wide, and the output video path being r bits wide, r≦(q+p), wherein the circuit includes an error propagation circuit ( 60 – 70 ) at the output of the adder ( 10 ) and/or at the output of the processing means ( 32 – 40 ), M least significant bits of the gamma-corrected video signal of each pixel being delayed by one pixel and added to the gamma-corrected video signal of the following next pixel.