Technique for simulating film grain using frequency filtering
AssigneeThomson Licensing
InventorsJoan Llach, Jill MacDonald Boyce, Alexandros Tourapis
Life of this patent
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Abstract
Simulation of film grain in an image can occur by compressing a video image, then transmitting compressed video together with a message containing at least one parameter indicative of the original film grain, to a decoder, and restoring the original grainy appearance of images by having the decoder simulating film grain based on the content of the film grain message. To improve efficiency, one or more parameters of film grain information undergo scaling in accordance with a target pixel block size for pixel blocks in the image. Such scaling allows for the use of conventional circuitry for performing block-based operations in connection with the film grain simulation.
Claims17
A method for simulating film grain comprising the steps of:
- receiving image information;
- receiving film grain information that includes horizontal and vertical cut frequencies specifying at least one attribute of the film grain previously in the image;
- and
- simulating the film grain in accordance with the horizontal and vertical cut frequencies scaled to the nearest lower and higher integers, respectively, the scaling in accordance with a target pixel block size for pixel blocks in the image containing the film grain to be simulated.
A method for simulating film grain, comprising the steps of
- (a) receiving image information representative of an image from which film grain has been at least attenuated;
- (b) receiving film grain information that includes horizontal and vertical cut frequencies specifying at least one attribute of the film grain previously in the image;
- (c) scaling the horizontal and vertical cut frequencies to the nearest lower and higher integers, respectively, for target pixel blocks in the image containing the film grain to be simulated when the blocks have a size different from 16×16 blocks;
- (d) reading a successive one of pixel blocks of the image;
- (e) generating random noise for the successive pixel block in accordance with the at least one attribute;
- (f) scaling the random noise to change the pixel values of the pixel blocks previously scaled to the target block size;
- (g) performing a block-based transform on the scaled noise to yield a set of coefficients;
- (h) frequency filtering the coefficients;
- and
- (i) performing an inverse block-based transform on the frequency filtered coefficient to yield a film grain image block.
A method for simulating film grain, comprising the steps of
- (a) receiving image information representative of an image from which film grain has been at least attenuated;
- (b) receiving film grain information that includes horizontal and vertical cut frequencies specifying at least one attribute of the film grain previously in the image;
- (c) scaling the horizontal and vertical cut frequencies to the nearest lower and higher integers, respectively, for target pixel blocks in the image containing the film grain to be simulated when the blocks have a size different from 16×16 blocks;
- (d) reading a successive one of pixel blocks of the image;
- (e) generating random noise for the successive pixel block in accordance with the at least one attribute;
- (f) performing a block-based transform on the noise to yield a set of coefficients;
- (g) frequency filtering the coefficients;
- (h) performing an inverse block-based transform on the frequency filtered coefficient to yield a film grain image block;
- and
- (i) scaling the noise to change the pixel values of the pixel blocks previously scaled to the target block size.
Dependencies are inferred from the claim text.