Patent EP0586074A2 successfully refreshed from Google Patents.
EP0586074A2
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EP
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Image processing apparatus suitable for multistage compression
Assignee: Canon Inc
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Filing: 1993-07-22
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Granted: —
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Expires: 2013-07-22
Abstract
Abstract Disclosed are an image processing method and an image processing apparatus capable of controlling the quantity of coded data to a target data quantity. Quantized coefficients are coded by a Huffman coder 14, and the coded data and the code lengths are stored in a buffer memory 15. The code lengths are also supplied to a code length accumulator 17, and the accumulation result is compared with values of a threshold value table 19 by a comparator 18. On the basis of the index (comparison result) from the comparator 18, a reference value from a reference value calculator 16, and the code length accumulated value from the buffer memory 15, a stage determining unit 20 determines a stage to which the coded data and the code lengths in the buffer memory 15 are allocated, and outputs the stage as a stage number.
Inventors
- 👤 Kazuhiro c/o Canon Kabushiki Kaisha Saito
- 👤 Yukari C/O Canon Kabushiki Kaisha Shimomura
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 18:12
CPC Classifications
H; H04; H04N; H04N11/00; H04N11/04; H04N11/042; H04N11/044; H04N1/00; H04N1/41; H04N1/46; H04N1/64; H04N1/642; H04N19/00; H04N19/10; H04N19/102; H04N19/124; H04N19/126; H04N19/132; H04N19/134; H04N19/154; H04N19/169; H04N19/18; H04N19/184; H04N19/46; H04N19/13; H04N19/146; H04N19/30; H04N19/60; H04N19/90; H04N19/91
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
96 words
An image processing apparatus for coding frequency coefficients in units of blocks, and outputting code data divisionally in a plurality of stages, comprising: coding means for coding the frequency coefficients in units of blocks; monitoring means for monitoring an amount of code data which has coded by said coding means; allocating means for allocating stage information to the code data from said coding means on the basis of the amount of code data monitored by said monitoring means; and output means for outputting the code data from said coding means in accordance with the stage information.
Claim 2
Dependent Claim
99 words
The apparatus according to claim 1, wherein said monitoring means comprises: storing means for storing a number of codes for each stage, which is allocated beforehand as a threshold value to that stage; comparing means for receiving from said monitoring means a number of total code data output from said coding means as total code quantity and comparing the number of code data with a threshold value read out from said storing means; and determining means for determining a stage information for the code data from said coding means in accordance with the comparison result of said comparing means.
Claim 3
Dependent Claim
80 words
The apparatus according to claim 1, wherein said monitoring means comprises: storing means for storing a code quantity for each stage, which is allocated beforehand as a threshold value to that stage; comparing means for comparing a total code quantity from said monitoring means with a threshold value read out from said storing means; and determining means for determining a stage information for the code data from said coding means in accordance with the comparison result from said comparing means.
Claim 4
Dependent Claim
67 words
The apparatus according to claim 1, wherein said output means comprises: data storing means, divided into segments each having a predetermined unit size, for storing a plurality of code data; checking means for checking a free capacity of each segment; and table means for storing a correspondence between each segment of said data storing means and a stage to which code data stored in that segment belongs.
Claim 5
Dependent Claim
68 words
The apparatus according to claim 4, wherein said output means comprises means for, when said checking means determines that no area for storing new code data belonging to a stage allocated to a given segment is present in the searched segment, searching for an unused segment in said data storing means, storing the new code data in that unused segment, and updating the data in said table means.
Claim 6
Dependent Claim
26 words
The apparatus according to claim 4, wherein said output means allocates a segment closest to the segment being currently used in searching for an unused segment.
Claim 7
Dependent Claim
30 words
The apparatus according to claim 4, wherein when no empty area is present in said data storing means, said output means frees segments storing coded data belonging to subsequent stages.
Claim 8
Dependent Claim
29 words
The apparatus according to claim 1, wherein said output means outputs a pair of one code data and stage information allocated to that code data by said allocating means.
Claim 9
Dependent Claim
23 words
The apparatus according to claim 1, wherein the frequency components of the image are extracted by orthogonal transformation and coded using Huffman codes.
Claim 10
Dependent Claim
26 words
The apparatus according to claim 1, wherein the frequency components of the image are input by a known frequency sequence and coded by said coding means.
Claim 11
Dependent Claim
24 words
The apparatus according to claim 10, wherein the frequency components of the image are arranged in an order from lower-frequency components to higher-frequency components.
Claim 12
Dependent Claim
77 words
An image processing method of coding frequency coefficients in units of blocks, and outputting code data divisionally in a plurality of stages, comprising the steps of: coding frequency coefficients in units of blocks; monitoring an amount of code data which has been obtained in the coding step; allocating stage information to the code data on the basis of the amount of code obtained by the monitoring; and outputting the code data in accordance with the stage information.
Claim 13
Dependent Claim
66 words
The method according to claim 12, wherein the monitoring step comprises the substeps of: storing a number of codes for each stage, which is allocated beforehand as a threshold value to that stage; monitoring a number of the input codes as total code quantity and comparing the total code quantity with a readout threshold value; and determining a stage information in accordance with the comparison result.
Claim 14
Dependent Claim
53 words
The method according to claim 12, wherein the monitoring step comprises the substeps of: storing a code quantity for each stage, which is allocated beforehand as a threshold value to that stage; comparing a total code quantity with a readout threshold value; and determining a stage information in accordance with the comparison result.
Claim 15
Dependent Claim
112 words
The method according to claim 12, wherein the output step comprises the substeps of: checking free capacities of individual segments of data storing means divided into the segments each having a predetermined unit size; and when it is determined that no area for storing new coded data belonging to a stage allocated to a given segment is present in that segment, searching for an unused segment in said data storing means, storing the new coded data in the searched unused segment, and updating the data in a table for storing a correspondence between each segment of said data storing means and a stage to which coded data stored in that segment belongs.
Claim 16
Dependent Claim
26 words
The method according to claim 15, wherein the output step allocates a segment closest to the segment being currently used in searching for an unused segment.
Claim 17
Dependent Claim
30 words
The method according to claim 15, wherein when no empty area is present in said data storing means, the output step frees segments storing coded data belonging to subsequent stages.
Claim 18
Dependent Claim
25 words
The method according to claim 12, wherein the output step outputs a pair of one coded data and stage information allocated to that coded data.
Claim 19
Dependent Claim
23 words
The method according to claim 12, wherein the frequency components of the image are extracted by orthogonal transformation and coded using Huffman codes.
Claim 20
Dependent Claim
89 words
An image processing method of quantizing an image in a frequency space, coding the quantized frequency coefficients in units of blocks, and outputting the coded data divisionally in a plurality of stages, comprising the steps of: coding a quantized frequency coefficients in units of blocks; accumulating code lengths of the coded data obtained in the coding step; determining a stage on the basis of an accumulation result obtained in the accumulating step; and outputting the coded data in accordance with the determination result obtained in the stage determining step.
Claim 21
Dependent Claim
137 words
An image processing apparatus for compressing image data input in block sequence by using different compression methods, comprising: first compressing means for compressing input block sequential image data by a reversible compression method; second compressing means for compressing the block sequential image data by an irreversible compression method in accordance with the compression result from said first compressing means, and outputting the compressed data divisionally in a plurality of stages; determining means for determining the characteristic feature of a block on the basis of the compressed data obtained by said first compressing means; selecting means for selecting one of the compressed data obtained by said first and second compressing means on the basis of the characteristic feature obtained by said determining means; and output means for outputting the selected compressed data divisionally in a plurality of stages.
Claim 22
Dependent Claim
16 words
The apparatus according to claim 21, wherein said determining means determines characters, graphics, or natural images.
Claim 23
Dependent Claim
42 words
The apparatus according to claim 22, wherein characters, graphics, or natural images are compressed and output by said first compressing means, natural images are compressed by said second compressing means, and the compressed data are divisionally output in a plurality of stages.
Claim 24
Dependent Claim
94 words
An image processing apparatus for quantizing an image in a frequency space, coding the quantized frequency coefficients in units of blocks, and outputting the coded data divisionally in a plurality of stages, comprising: coding means for coding the quantized frequency coefficients in units of blocks; counting means for counting the coded data obtained by said coding means; stage determining means for determining a stage on the basis of the count result from said counting means; and output means for outputting the coded data in accordance with the determination result from said stage determining means.
Claim 25
Dependent Claim
42 words
A block based method of image coding wherein the set of coefficients for each block is divided into a number of subsets, and these subsets are included selectively in the output data so as to remain within a predetermined code size limit.
Claim 26
Independent Claim
51 words
A method of image compression wherein different compression methods are available for different image content types, wherein the image content type and compression method to be used are selected automatically on the basis of the results of applying one or other of the compression methods to the image part of interest.
References Cited (Backward Citations)
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