Film grain simulation method based on pre-computed transform coefficients
AssigneeThomson Licensing
InventorsCristina Gomila, Joan Llach
Life of this patent
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Abstract
Film grain simulation within a receiver occurs by first obtaining at least one block of pre-computed transformed coefficients. The block of pre-computed transformed coefficients undergoes filtering responsive to a frequency range that characterizes a desired pattern of the film grain. In practice, the frequency range lies within a set of cut frequencies fHL, fVL, fHH and fVH of a filter in two dimensions that characterizes a desired film grain pattern. Thereafter, the filtered set of coefficients undergoes an inverse transform to yield the film grain pattern.
Claims16
A method for simulating film grain in a decoded video stream, comprising:
- (a) obtaining a pre-computed block of transformed coefficients;
- (b) frequency filtering the transformed coefficients responsive to a frequency range that characterize a desired pattern of film grain;
- (c) performing an inverse transform on the frequency-filtered transformed coefficients;
- and
- (d) combining a block of film grain obtained by inverse transformation of the frequency-filtered transformed coefficients with the decoded video stream.
Apparatus for simulating film grain in a decoded video stream, comprising:
- a first memory for storing at least one a pre-computed block of transformed coefficients;
- at least one of a programmed processor, and dedicated logic circuit for simulating film grain in the decoded video stream by (a) obtaining a pre-computed block of transformed coefficients from the memory;
- (b) frequency filtering the transformed coefficients responsive to a frequency range that characterize a desired pattern of film grain;
- (c) performing an inverse transform on the frequency-filtered transformed coefficients;
- and
- (d) combining a block of film grain obtained by inverse transformation of the frequency-filtered transformed coefficients with the decoded video stream.
Apparatus for simulating film grain in a decoded video stream, comprising:
- a first memory for storing at least one a pre-computed block of transformed coefficients;
- means for obtaining a pre-computed block of transformed coefficients from the memory;
- means for frequency filtering the transformed coefficients responsive to a frequency range that characterize a desired pattern of film grain;
- means for performing an inverse transform on the frequency-filtered transformed coefficients;
- and
- means for combining a block of film grain obtained by inverse transformation of the frequency-filtered transformed coefficients with the decoded video stream.
Dependencies are inferred from the claim text.