Decoding apparatus, decoding method, and storage medium
First Claim
Patent Images
1. A decoding apparatus for decoding encoded data including a code set constituted by a code word that indicates a group number and by additional information that is composed of bits, wherein a first bit of the additional information indicates positive or negative, and the additional information specifies one of decoding values belonging to a group specified by the code word, comprising:
- an input unit that inputs the encoded data;
a decoding unit that decodes the encoded data in units of code sets;
a detecting unit that detects, out of the input encoded data, an incomplete code set from which additional information is missing at least partly including the code word and the first bit of the additional information; and
a supplying unit that generates an alternate code set that replaces the incomplete code set, based on the code word constituting the incomplete code set and on whether the first bit of the additional information constituting the incomplete code set indicates positive or negative, and supplies the generated alternate code set to the decoding unit.
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Abstract
A decoding apparatus acquires, from encoded data, a piece of additional bits that have been partly cut off, acquires, from the piece of the additional bits, the number of bits that are missing due to the cutting off as the number of missing bits, and restores the additional bits by reproducing the missing bits.
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Citations
12 Claims
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1. A decoding apparatus for decoding encoded data including a code set constituted by a code word that indicates a group number and by additional information that is composed of bits, wherein a first bit of the additional information indicates positive or negative, and the additional information specifies one of decoding values belonging to a group specified by the code word, comprising:
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an input unit that inputs the encoded data; a decoding unit that decodes the encoded data in units of code sets; a detecting unit that detects, out of the input encoded data, an incomplete code set from which additional information is missing at least partly including the code word and the first bit of the additional information; and a supplying unit that generates an alternate code set that replaces the incomplete code set, based on the code word constituting the incomplete code set and on whether the first bit of the additional information constituting the incomplete code set indicates positive or negative, and supplies the generated alternate code set to the decoding unit. - View Dependent Claims (11)
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2. A decoding apparatus for decoding encoded data of a preset fixed bit length L, and including a code set constituted by a code word that indicates a group number and by additional information that is composed of bits, wherein a first bit of the additional information indicates positive or negative, and the additional information is of a number of bits indicated by a group specified by the code word, comprising:
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an input unit that inputs the encoded data; a decoding unit that decodes the encoded data in units of code sets; a determining unit that extracts the code set from a beginning of the encoded data input by the input unit, determines whether a final bit position of the extracted code set of interest is at or before the fixed length L, and, if the final bit position of the extracted code set of interest is after the fixed length L, determines whether a first bit position of the additional information included in the extracted code set of interest is at or before the fixed length L; a first supplying unit that, if a determination result of the determining unit indicates that the final bit position of the extracted code set of interest is at or before the fixed length L, supplies the extracted code set of interest to the decoding unit; and a second supplying unit that, if a determination result of the determining unit indicates that the final bit position of the extracted code set of interest is after the fixed length L, and that the first bit position of the additional information included in the extracted code set of interest is at or before the fixed length L, generates an alternate code set that replaces the code set of interest, and supplies the generated alternate code set to the decoding unit, wherein the second supplying unit judges how many bits of additional information are missing, from the group specified by the code word of the code set of interest, generates additional information capable of being represented with non-missing bits, and supplies the code word followed by the generated additional information to the decoding unit as the alternate code set. - View Dependent Claims (12)
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3. A decoding apparatus for decoding an image from encoded data truncated to a fixed length when the image was encoded by cutting off an end of data including a combination of a code word and additional bits that represent a frequency component, comprising:
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decrypting means for acquiring, from the encoded data, a piece of the additional bits that have been partly cut off; and correcting means for acquiring, from the piece of the additional bits, a number of bits missing due to the cutting off, as a number of missing bits, and restores the additional bits by reproducing the missing bits, wherein the correcting means reproduces the additional bits by adding “
0”
for the number of missing bits to a tail of the piece of the additional bits if an MSB, which is a most significant bit of the piece of the additional bits from which bits are missing due to the cutting off, is “
1”
, and by adding “
1”
for the number of missing bits to the tail of the piece of the additional bits if the MSB is “
0”
. - View Dependent Claims (4, 5, 6, 7)
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8. A decoding method for decoding encoded data including a code set constituted by a code word that indicates a group number and by additional information that is composed of bits, wherein a first bit of the additional information indicates positive or negative, and the additional information specifies one of decoding values belonging to a group specified by the code word, comprising:
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an inputting step of inputting the encoded data; a decoding step of decoding the encoded data in units of code sets; a detecting step of detecting, out of the input encoded data, an incomplete code set from which additional information is missing at least partly including the code word and the first bit of the additional information; and a supplying step of generating an alternate code set that replaces the incomplete code set, based on the code word constituting the incomplete code set and on whether the first bit of the additional information constituting the incomplete code set indicates positive or negative, and supplying the generated alternate code set to the decoding step.
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9. A decoding method performed by a decoding apparatus for decoding encoded data of a preset fixed bit length L and including a code set constituted by a code word that indicates a group number and by additional information that is composed of bits, wherein a first bit of the additional information indicates positive or negative, and the additional information is of a number of bits indicated by a group specified by the code word, comprising:
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an inputting step of inputting the encoded data; a decoding step of decoding the encoded data in units of code sets; a determining step of extracting the code set from a beginning of the encoded data input in the input step, determining whether a final bit position of the extracted code set of interest is at or before the fixed length L, and, if the final bit position of the extracted code set of interest is after the fixed length L, determining whether a first bit position of the additional information included in the code set of interest is at or before the fixed length L; a first supplying step of, if a determination result in the determining step indicates that the final bit position of the code set of interest is at or before the fixed length L, supplying the code set of interest to the decoding step; and a second supplying step of, if a determination result in the determining step indicates that the final bit position of the code set of interest is after the fixed length L, and that the first bit position of the additional information included in the code set of interest is at or before the fixed length L, generating an alternate code set that replaces the code set of interest, and supplying the generated alternate code set to the decoding step, wherein in the second supplying step, how many bits of additional information are missing is judged from the group specified by the code word of the code set of interest, additional information capable of being represented with non-missing bits is generated, and the code word followed by the generated additional information is supplied to the decoding step as the alternate code set.
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10. A decoding method performed by a decoding apparatus provided with means for decoding an image from encoded data truncated to a fixed length when the image was encoded by cutting off an end of data including a combination of a code word and additional bits that represent a frequency component, comprising:
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a decrypting step of acquiring, from the encoded data, a piece of the additional bits that have been partly cut off; and a correcting step of acquiring, from the piece of the additional bits, a number of bits missing due to the cutting off, as a number of missing bits, and restoring the additional bits by reproducing the missing bits, wherein in the correcting step, the additional bits are reproduced by adding “
0”
for the number of missing bits to a tail of the piece of the additional bits if an MSB, which is a most significant bit of the piece of the additional bits from which bits are missing due to the cutting off, is “
1”
, and by adding “
1”
for the number of missing bits to the tail of the piece of the additional bits if the MSB is “
0”
.
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Specification