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EP0530022A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Apparatus for encoding am image signal

Assignee: Fujifilm Business Innovation Corp
•
Filing: 1992-08-27
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Granted: —
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Expires: 2012-08-27
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Abstract

Abstract Apparatus for encoding an image signal which is capable of improving the quality of a reproduced image with respect to not only a general image in which electric power is concentrated in low-region coefficients but also an image where the electric power is concentrated in a high region. The apparatus comprises a blocking device in which a rectangular area in an image is detected from a digital image signal as a pixel block, and is subjected to an orthogonal transform by a converter to obtain a transformed coefficient. In addition, an activity calculator calculates the variance of the image within the block, and electric power to be preserved during encoding is determined by a power-preservation-rate determining device on the basis of the variance determined. An optimum mask is selected by a mask selector on the basis of a transformed coefficient from the converter and a power preservation rate from the power-preservation-rate determining device, and the selection of the transformed coefficient is performed by a coefficient selector by means of this mask. The transformed coefficient after being selected is quantized by a quantizer, is encoded to be outputted through a transmission line.

Inventors

  • 👤 Kazuhiro c/o Fuji Xerox Co Ltd Suzuki
  • 👤 Koh C/O Fuji Xerox Co Ltd Kamizawa
  • 👤 Yutaka C/O Fuji Xerox Co Ltd Koshi
  • 👤 Setsu C/O Fuji Xerox Co Ltd Kunitake

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-10-31 04:33
CPC Classifications
H; H04; H04N; H04N19/00; H04N19/50; H04N19/59; H04N19/10; H04N19/134; H04N19/136; H04N19/14; H04N19/154; H04N19/169; H04N19/17; H04N19/176; H04N19/18; H04N19/90; H04N19/94; H04N19/102; H04N19/124; H04N19/132; H04N19/60

Claims Analysis

Total Claims: 7
Claim 1
Independent Claim 157 words
An apparatus for encoding an image signal in which the image signal is formed into blocks to be subjected to an orthogonal transform, and a transformed coefficient is coded, comprising: means for dividing the image signal into pixel blocks; means for performing a two-dimensional orthogonal transform with respect to each of said pixel blocks; means for determining a ratio of electric power to be preserved during coding, in correspondence with the characteristic of each of said pixel blocks; determining means for determining the significance of each of the transformed coefficients in a decreasing order of electric power, the determination being continued until the sum total of electric power of AC coefficients determined to be significant exceeds said ratio of electric power with respect to the sum total of total ac power within the block; and encoding means for encoding as 0 a coefficient which has not been determined to be significant, on the basis of the determination.
Claim 2
Dependent Claim 44 words
The apparatus for encoding an image signal as defined in claim 1 wherein said determining means comprises means for calculating an in-block variance of the pixel block, the ratio of electric power being determined on the basis of the variance determined through a calculation.
Claim 3
Dependent Claim 33 words
The apparatus for encoding an image signal as defined in claim 1 wherein said determining means determines the transformed coefficients subjected to quantization to be significant in a decreasing order of electric power.
Claim 4
Dependent Claim 42 words
The apparatus for encoding an image signal as defined in claim 1 further comprising: means for calculating an in-block variance of the transformed coefficients subjected to an orthogonal transform, the ratio of electric power being determined on the basis of calculation thereof.
Claim 5
Independent Claim 179 words
An apparatus for encoding an image signal in which the image signal is formed into blocks and is subjected to an orthogonal transform, and a transformed coefficient is coded, comprising: means for dividing the image signal into pixel blocks; means for performing a two-dimensional orthogonal transform with respect to each of said pixel blocks; waveform analyzing means for comparing the waveform in each of the pixel blocks with a plurality of typical patterns to output identification information for identifying a most similar typical pattern; storage means for storing a plurality of items of mask information representing the significance or insignificance of each of the transformed coefficients obtained by said means for performing a two-dimensional orthogonal transform; mask selecting means for selecting the mask information from said storage means on the basis of the identification information from said waveform analyzing means; coefficient selecting means for determining the significance or insignificance of the transformed coefficient by using the mask information selected to set to 0 the transformed coefficient determined to be insignificant; and encoding means for encoding the post-selection transformed coefficient.
Claim 6
Dependent Claim 37 words
The apparatus for encoding an image signal as defined in claim 5 wherein said waveform analyzing means carries out pattern matching to compare the waveform in each of the pixel blocks with the plurality of typical patterns.
Claim 7
Dependent Claim 42 words
The apparatus for encoding an image signal as defined in claim 5 further comprising means for calculating activity in the pixel block, wherein said mask selecting means selects mask information from said storage means by using the identification information and the activity.

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