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EP0469835A2
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Image processing apparatus and method
Assignee: Canon Inc
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Filing: 1991-07-29
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Granted: —
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Expires: 2011-07-29
Abstract
Abstract This disclosure relates to an apparatus and method for orthogonally transforming and quantizing, in block units, inputted image data, and subsequently performing image compression by variable-length coding the data. In particular, control is performed in such a manner that the compressed information quantity attains a predetermined quantity when variable-length coding is carried out. Optimum image compression and expansion are performed by scanning data quantized upon taking into consideration the output characteristics of an image output unit and human visual characteristics. Further, by selecting an optimum quantization table in coding or selecting optimum results from a plurality of coded results, management of the image memory is facilitated, and image compression and expansion featuring ease of image editing and treatment can be performed while image quality is maintained. Furthermore, control is executed in such a manner that data access to the image memory attains a predetermined value so as to make possible the combining of images in the image memory.
Inventors
- 👤 Hideo Honma
- 👤 Hisashi Ishikawa
- 👤 Nobutaka Miyake
- 👤 Yoshitake Nagashima
- 👤 Takashi Saito
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 00:47
CPC Classifications
H; H04; H04N; H04N19/00; H04N19/42; H04N19/436; H04N19/10; H04N19/102; H04N19/124; H04N19/126; H04N19/134; H04N19/146; H04N19/15; H04N19/164; H04N19/169; H04N19/17; H04N19/176; H04N19/189; H04N19/192; H04N19/196; H04N19/197; H04N19/60; H04N19/13; H04N19/152; H04N19/90; H04N19/91
Claims Analysis
Total Claims: 41
Claim 1
Independent Claim
67 words
An image processing apparatus comprising: orthogonal transformation means for orthogonally transforming inputted data in block units; quantizing means for quantizing the data orthogonally transformed by said orthogonal transformation means; coding means for variable-length coding the data quantizing by said quantizing means; and control means for controlling the quantity of the coded data output from said coding means to be less than a predetermined quantity in block units.
Claim 2
Dependent Claim
38 words
The apparatus according to claim 1, wherein said control means includes adjusting means for controlling said quantizing means based upon the data quantity after variable-length coding, and adjusting the data quantity after variable-length coding to said predetermined quantity.
Claim 3
Dependent Claim
24 words
The apparatus according to claim 2, wherein said adjusting means has a quantization table and controls the data quantity based upon said quantization table.
Claim 4
Dependent Claim
39 words
The apparatus according to claim 2, wherein said adjusting means has round-down means for rounding down data which exceeds the predetermined quantity, said memory means being supplied with data after the data is rounded down by said round-down means.
Claim 5
Dependent Claim
31 words
The apparatus according to claim 2, wherein said adjusting means has a plurality of quantization tables and controls the data quantity by performing a changeover among said plurality of quantization tables.
Claim 6
Dependent Claim
27 words
The apparatus according to claim 5, wherein said adjusting means further includes selecting means for selecting an optimum quantization table from among the plurality of quantization tables.
Claim 7
Dependent Claim
41 words
The apparatus according to claim 1, wherein said coding means includes a Huffman coding circuit having a plurality of Huffman code tables, said Huffman coding circuit being controlled by changing over the plurality of Huffman code tables by said control means.
Claim 8
Dependent Claim
128 words
An image processing apparatus for controlling the data quantity of every block to be less than a predetermined value when inputted data is coded, comprising: transformation means for orthogonally transforming the inputted data in block units; quantizing means for quantizing the data orthogonally transformed by said transformation means; scanning means for scanning the data quantized by said quantizing means; coding means for performing variable-length coding based upon the data scanned by said scanning means; counting means for counting quantity of coded data generated by said coding means; comparing means for comparing the code quantity counted by said counting means and a predetermined quantity for every block; and changeover means for changing over quantization conditions of said quantizing means based upon results of comparison performed by said comparing means.
Claim 9
Dependent Claim
25 words
The apparatus according to claim 8, wherein said coding means at least codes an orthogonal transformation component which is assured a band within the block.
Claim 10
Dependent Claim
20 words
The apparatus according to claim 8, wherein said changeover means changes over said quantization conditions by changeover of quantization tables.
Claim 11
Dependent Claim
29 words
The apparatus according to claim 8, wherein said changeover means changes over said quantization conditions by changing over a value of a coefficient which multiplies a quantization step value.
Claim 12
Dependent Claim
29 words
The apparatus according to claim 8, wherein when said inputted data is color image data, an orthogonal transformation component which is assured a band is capable of being varied.
Claim 13
Dependent Claim
74 words
An image processing apparatus having a plurality of quantization tables for quantizing image data in block units comprising: quantizing means for quantizing the image data in block units based upon any of the quantization tables; counting means for counting data quantity of the quantized image data quantized by said quantizing means in block units; and selecting means for selecting a quantization table in dependence upon the result of counting performed by said counting means.
Claim 14
Dependent Claim
30 words
The apparatus according to claim 13, wherein said selecting means selects a quantization table in a direction in which the data quantity of the quantized image data decreases or increases.
Claim 15
Dependent Claim
22 words
The apparatus according to claim 13, wherein said selecting means includes memory means for storing an index of the selected quantization table.
Claim 16
Dependent Claim
58 words
An image processing apparatus comprising: input means for inputting image data; coding means for subjecting the image data inputted by said input means to a plurality of coding processing operations which differ from one another; and selecting means for selecting one result from among the results of the plurality of coding processing operations obtained by said coding means.
Claim 17
Dependent Claim
35 words
The apparatus according to claim 16, wherein said selecting means ends selection of said result during the time that said coding means codes the image data from the beginning to the end of every block.
Claim 18
Dependent Claim
24 words
The apparatus according to claim 16, wherein said selecting means makes a selection in conformity with time required for coding by said coding means.
Claim 19
Dependent Claim
30 words
The apparatus according to claim 16, wherein, among the plurality of coding processing operations applied to the image data, processing performed in common is executed separate from said coding means.
Claim 20
Dependent Claim
21 words
The apparatus according to claim 19, wherein the processing performed in common is an orthogonal transformation applied to the image data.
Claim 21
Dependent Claim
84 words
An image processing apparatus comprising: orthogonal transformation means for orthogonally transforming input image data in block units; coding means for quantizing the data orthogonally transformed by said orthogonal transformation means, and coding a quantized transformation coefficient to generate variable-length coded data of which quantity is less than a predetermined quantity in block units; and memory means for storing the data, which has been coded by said coding means; wherein data stored in said memory means is capable of being read out in block units.
Claim 22
Dependent Claim
47 words
The apparatus according to claim 21, wherein said coding means performs a plurality of coding operations having different information quantities after coding, and executes coding processing upon selecting a coding method such that quantity of coded data is closest to the predetermined quantity without exceeding the quantity.
Claim 23
Dependent Claim
28 words
The apparatus according to claim 22, wherein joint use is made of said orthogonal transformation means when the plurality of coding operations is performed by said coding means.
Claim 24
Dependent Claim
79 words
The apparatus according to claim 23, wherein said coding means has partitioning means for partitioning a transformation coefficient, after an orthogonal transformation by said orthogonal transformation means, into at least two hierarchical layers every block, wherein when coding is performed, coding is carried out successively from a most significant layer, and coded data up to a hierarchical layer in which data quantity after coding of one block does not exceed the predetermined quantity is stored in said memory means.
Claim 25
Dependent Claim
69 words
An image processing method comprising the steps of: an orthogonal transformation step of orthogonally transforming inputted data in block units; a quantizing step of quantizing the data orthogonally transformed at said orthogonal transformation step; and a coding step of variable-length coding the data quantized at said quantizing step by performing control in such a manner that the information quantity of the data becomes a predetermined quantity in block units.
Claim 26
Dependent Claim
140 words
An image processing method for controlling data quantity of every block to be less than a predetermined value when inputted data is coded, comprising the steps of: a transforming step of orthogonally transforming the inputted data in block units; a quantizing step of quantizing the data orthogonally transformed at said transforming step; a scanning step of scanning the data quantized at said quantizing step; a coding step of performing variable-length coding based upon the data scanned at said scanning step; a counting step of counting data quantity generated when variable-length coding is performed at said coding step; a comparing step of comparing the data quantity counted at said counting step and a predetermined quantity for every block; and a changeover step of changing over quantization conditions of said quantizing step based upon results of comparison performed at said comparing step.
Claim 27
Dependent Claim
84 words
An image processing method using a plurality of quantization tables for quantizing image data in block units comprising the steps of: a quantizing step of quantizing the image data in block units based upon any of the quantization tables; a counting step of counting data quantity of the quantized image data quantized at said quantized step; and a selecting step of selecting a quantization table, from among the plurality of quantization tables, in dependence upon the result of counting performed at said counting step.
Claim 28
Dependent Claim
64 words
An image processing method comprising the steps of: an input step of inputting image data; a coding step of subjecting the image data inputted at said input step to a plurality of coding processing operations which differ from one another; and a selecting step of selecting one result from among the results of the plurality of coding processing operations obtained at said coding step.
Claim 29
Dependent Claim
91 words
An image processing method comprising the steps of: an orthogonal transformation step of orthogonally transforming input image data in block units; a coding step of quantizing the data orthogonally transformed at said orthogonal transformation step, and coding a quantized transformation coefficient to generate variable-length coded data of which quantity is less than a predetermined quantity in block units; a storing step of storing the data, which has been coded at said coding step; and a reading step of reading data, which has been stored at said storing step, in block units.
Claim 30
Dependent Claim
48 words
An image processing method comprising the steps of; a coding step of coding input image data by variable-length coding method; a control step of controlling a quantity of the coded image data in block units; and a storing step of storing the coded image data in a memory.
Claim 31
Dependent Claim
65 words
An image processing method comprising the steps of; a first coding step of coding input image data by first variable-length coding method; a second coding step of coding input image data by second variable-length coding method; and a selecting step of selecting the coded image data coded in said first or second coding step; wherein said first and second coding step perform coding in parallel.
Claim 32
Dependent Claim
39 words
An image processing apparatus comprising; coding means for coding input image data by variable-length coding method; control means for controlling a quantity of the coded image data in block units; and memory means for storing the coded image data.
Claim 33
Dependent Claim
21 words
The apparatus according to claim 32, wherein said coding means includes orthogonal transform means for orthogonally transforming the input image data.
Claim 34
Dependent Claim
24 words
The apparatus according to claim 33, wherein said coding means further includes quantization means for quantizing the data transformed by said orthogonal transform means.
Claim 35
Dependent Claim
24 words
The apparatus according to claim 34, wherein said coding means further includes means for performing Huffman-coding for the data quantized by said quantization means.
Claim 36
Dependent Claim
22 words
The apparatus according to claim 32, wherein said control means includes counting means for counting the quantity of the coded image data.
Claim 37
Dependent Claim
43 words
An image processing apparatus comprising; first coding means for coding image data by first variable-length coding method; and second coding means for coding image data by second variable-length coding method; wherein said first and second coding means are operable at the same time.
Claim 38
Dependent Claim
24 words
The apparatus according to claim 37, wherein said first and second coding means include orthogonal transform means for orthogonally transforming the input image data.
Claim 39
Dependent Claim
27 words
The apparatus according to claim 38, wherein said first and second coding means further include quantization means for quantizing the data transformed by said orthogonal transform means.
Claim 40
Dependent Claim
27 words
The apparatus according to claim 39, wherein said first and second coding means further include means for performing Huffman-coding for the data quantized by said quantization means.
Claim 41
Dependent Claim
29 words
The apparatus according to claim 37, further including selecting means for selecting the encoded image data outputted by said first and second coding means in accordance with data quantity.
References Cited (Backward Citations)
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