Signal processing apparatus and signal processing method performing gamma correction
View Patent ↗A difference sample data holder of a gamma correction device holds as difference sample data a difference between a corrected signal level and a yet-to-be-corrected signal level for each of multiple sample points set at equal intervals between the permissible minimum and maximum levels of an input video signal. A correction execution unit performs cubic interpolation operation using the difference sample data held in the difference sample data holder, and adds the operated result and the signal level of the input video signal to obtain the signal level of the corrected video signal.
1. A signal processing apparatus, comprising:
a coefficient selector which selects a group of kernel coefficients among a plurality of kernel coefficients based on a first portion of a video data;
a difference sample data selector which selects a group of difference sample data among a plurality of difference sample data based on a second portion of the video data;
an interpolation operation unit which performs a cubic interpolation operation based on the group of kernel coefficients and the group of difference sample data to produce an interpolation data;
an adder which adds the video data with the interpolation data to produce a gamma correction video signal; and
a sign determination unit which adds the interpolation data with a sign of a positive value in a first correction mode and adds the interpolation data with a sign of a negative value in a second correction mode,
wherein the adder receives the interpolation data added with the sign as the interpolation data.
2. The signal processing apparatus as claimed in claim 1 , wherein the kernel coefficients are obtained in units of a quantization bit of the video data.
3. The signal processing apparatus as claimed in claim 1 , further comprising a kernel coefficient memory.
4. The signal processing apparatus as claimed in claim 3 , wherein the plurality of kernel coefficients is stored in the kernel coefficient memory.
5. A signal processing apparatus for performing a gamma correction on an input video signal, said signal processing apparatus comprising:
a difference sample data holder which holds, as difference sample data, a difference between a corrected signal level and a yet-to-be-corrected signal level for each of a plurality of sample points set at equal intervals between permissible minimum and maximum levels of the input video signal; and
a correction execution unit which performs a cubic interpolation operation using the difference sample data held in the difference sample data holder, and adds an operated result of the cubic interpolation operation and a signal level of the input video signal to obtain a signal level of a corrected video signal, wherein:
the correction execution unit includes a sign determination unit that assigns a sign to the operated result of the cubic interpolation operation, the sign depending on whether the gamma correction comprises a hard tone correction for correcting the input video signal to produce a hard tone or a soft tone correction for correcting the input video signal to produce a soft tone,
the correction execution unit adds the operated result, having the sign assigned by the sign determination unit, to the signal level of the input video signal, and
wherein the sign determination unit assigns a positive sign to the operated result when the gamma correction comprises the hard tone correction for correcting the input video signal.
6. The signal processing apparatus as claimed in claim 5 , wherein the sign determination unit assigns a negative sign to the operated result when the gamma correction comprises the soft tone correction for correcting the input video signal.
7. A signal processing apparatus for performing a gamma correction on an input video signal, said signal processing apparatus comprising:
a difference sample data holder which holds as difference sample data, a difference between a corrected signal level and a vet-to-be-corrected signal level for each of a plurality of sample points set at equal intervals between permissible minimum and maximum levels of the input video signal; and
a correction execution unit which performs a cubic interpolation operation using the difference sample data held in the difference sample data holder, and adds an operated result of the cubic interpolation operation and a signal level of the input video signal to obtain a signal level of a corrected video signal,
wherein a value of the corrected signal level is less than one half of a maximum value of the input video signal.
8. The signal processing apparatus as claimed in claim 7 , wherein a value of the yet-to-be corrected signal level is less than one half of a maximum value of the input video signal.