Optical information reproducing apparatus and optical information reproducing method
AssigneeHitachi Consumer Electronics Co., Ltd.
InventorsYusuke Nakamura, Hajime Ishihara
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Abstract
A method of calculating a reliability effective in a decoding process of hologram. An optical information reproducing apparatus that reproduces information with the use of the holography includes an image acquisition unit that reproduces two-dimensional data from a hologram disc, an image equalization unit that makes the two-dimensional data equal to target data having a target PR characteristic, a soft output decoding unit that decodes output data of the image equalization unit on the basis of the PR characteristic, and outputs a decoded result having a reliability, and an error correction unit that conducts an error correction of the data on the basis of the decoded result.
Claims6
An optical information reproducing apparatus that reproduces information with the use of holography, comprising:
- an image acquisition unit that acquires two-dimensional data from a hologram disc;
- a maximum likelihood path determination unit that outputs a maximum likelihood path which is a maximum likelihood decoded result of n-th pixel of the two-dimensional data;
- a competitive path determination unit that outputs a competitive path which is a decoded result different from the maximum likelihood path of the n-th pixel;
- a likelihood calculation unit that outputs a likelihood which is a difference between the maximum likelihood path of the n-th pixel and the competitive path of the n-th pixel;
- an inter-signal distance calculation unit that outputs an inter-signal distance which is a distance between a maximum likelihood waveform generated according to the decoded result of the maximum likelihood path of the n-th pixel, and a competitive waveform generated according to the decoded result of the competitive path of the n-th pixel;
- a normalized likelihood calculation unit that outputs a normalized likelihood obtained by normalizing the likelihood of the n-th pixel by the inter-signal distance of the n-th pixel;
- a reliability output unit that outputs a reliability on the basis of the likelihood candidate;
- and
- an error correction unit that conducts an error correction of data on the basis of the output of the reliability output unit.
An optical information reproducing method of reproducing information with the use of holography, comprising:
- acquiring two-dimensional data from a hologram disc;
- a maximum likelihood path determination step of outputting a maximum likelihood path which is a maximum likelihood decoded result of n-th pixel of the two-dimensional data;
- a competitive path determination step of outputting a competitive path which is a decoded result different from the maximum likelihood path of the n-th pixel;
- a likelihood calculation step of outputting a likelihood which is a difference between the maximum likelihood path of the n-th pixel and the competitive path of the n-th pixel;
- an inter-signal distance calculation step of outputting an inter-signal distance which is a distance between a maximum likelihood waveform generated according to the decoded result of the maximum likelihood path of the n-th pixel, and a competitive waveform generated according to the decoded result of the competitive path of the n-th pixel;
- a normalized likelihood calculation step of outputting a normalized likelihood obtained by normalizing the likelihood of the n-th pixel by the inter-signal distance of the n-th pixel;
- a reliability output step of outputting a reliability on the basis of the likelihood candidate;
- and
- an error correction step of conducting an error correction of data on the basis of output of the reliability output step.
Dependencies are inferred from the claim text.