EP0493086A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Data decoding apparatus
Assignee: Xerox Corp
•
Filing: 1991-12-23
•
Granted: —
•
Expires: 2011-12-23
Abstract
Abstract A decoder (10) for decoding CCITT compressed image data separates all the incoming codes into short codes and long codes, the short codes being sent to a short channel decoder (25), and the long codes being sent to a long channel decoder (28). At each decoding cycle either the long channel decoder or the short channel decoder is active. The short channel decoder has a twin set decoder (36) which decodes two short codes in parallel and guarantees two bits of decompressed data per decoding cycle. If the decoding of a first code generates a decompressed data of only one bit, then the decompressed data of a second code will be combined with the first decompressed data and the combination will be sent out. The long channel decoder decodes the long intermediate codes, which always generate at least four bits of decompressed data.
Inventors
- 👤 Jean-Swey Kao
- 👤 Simon M. Law
- 👤 Li-Fung Cheung
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 08:27
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/41; H04N1/411; H04N1/413; H04N1/417; H04N1/4175; H03; H03M; H03M7/00; H03M7/30; H03M7/40; H03M7/42; H03M7/425; H03M7/46
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
65 words
Apparatus for decoding compressed image data, comprising: means (18) for receiving and separating the compressed data image into short and long codes; short channel decoding means (25) connected to the separating means for receiving the short codes therefrom and for generating decompressed data; and long channel decoding means (28) connected to the separating means for receiving the long codes therefrom and for generating decompressed data.
Claim 2
Dependent Claim
65 words
Apparatus for decoding compressed image data, comprising: means (18) for receiving and separating the compressed data image into short and long codes; short channel decoding means (25) connected to the separating means for receiving the short codes therefrom and for generating decompressed data; and long channel decoding means (28) connected to the separating means for receiving the long codes therefrom and for generating decompressed data.
Claim 3
Dependent Claim
52 words
The apparatus as claimed in claim 1, wherein the short codes can generate a first minimum number of bits of decompressed data, and the long codes can generate a second minimum number of bits of decompressed data, the second minimum number of bits being greater than the first minimum number of bits.
Claim 4
Dependent Claim
27 words
The apparatus as claimed in claim 2, wherein the first minimum number of bits is one bit, and the second minimum number of bits is four bits.
Claim 5
Independent Claim
58 words
The apparatus as claimed in any preceding claim, wherein the short channel decoding means includes means (26) for receiving a first short code and a second short code from the separating means, and means (36) for generating in parallel a first decompressed data from the first short code and a second decompressed data from the second short code.
Claim 6
Dependent Claim
24 words
The apparatus as claimed in claim 4, further comprising means for merging the first and the second decompressed data into a single output path.
Claim 7
Dependent Claim
76 words
The apparatus as claimed in claim 4 to 5, further comprising means for determining if the first decompressed data has a given number of bits; and means responsive to the determining means to output only the first decompressed data if the first decompressed data has more than the given minimum number of bits, and to output the first and the second decompressed data if the first decompressed data has only the given minimum number of bits.
Claim 8
Independent Claim
34 words
A method for decoding compressed image data, comprising: a. separating the codes into short and long codes; b. generating decompressed data from the short codes, and c. generating decompressed data from the long codes.
Claim 9
Independent Claim
34 words
A method for decoding compressed image data, comprising: a. separating the codes into short and long codes; b. generating decompressed data from the short codes, and c. generating decompressed data from the long codes.
Claim 10
Dependent Claim
80 words
The method as claimed in claim 7, wherein the short codes can generate a first minimum number of bits of decompressed data, the long codes can generate a second minimum number of bits of decompressed data, the second minimum number of bits being greater than the first minimum number of bits, and wherein the step of separating the codes into short and long codes is in accordance with the minimum number of bits that can be generated by the codes.
Claim 11
Dependent Claim
27 words
The method as claimed in claim 8, wherein the first minimum number of bits is one bit, and the second minimum number of bits is four bits.
Claim 12
Independent Claim
38 words
The method as claimed in any of claims 7 to 9, comprising the further step of generating in parallel a first decompressed data from a first short code, and a second decompressed data from a second short code.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.