Facsimile and static presentation processing – Facsimile – Reduced time or bandwidth for static image communication
Reissue Patent
1996-05-29
2001-03-27
Vu, Kim Yen (Department: 2722)
Facsimile and static presentation processing
Facsimile
Reduced time or bandwidth for static image communication
C348S415100
Reissue Patent
active
RE037112
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a signal processing method for bandwidth compression coding of an image signal, and to a recording and reproducing device for recording this information to a recording medium such as an optical disk or a video tape and reproducing the information from this medium.
2. Prior art
Known image signal compression coding methods include in-field, in-frame, inter-field, and inter-frame. Inter-field and inter-frame coding use the correlation between the current field or frame and the fields or frames chronologically before and after the current field or frame to achieve a generally high compression ratio compared with in-field or in-frame compression coding, but requires in-frame or in-field coding to refresh the signal at a regular period because errors, when they occur, are propagated along the time axis.
During scene changes, however, when there is a significant change in the image, there is no time axis correlation between the adjacent fields or frames. Inter-field or inter-frame coding is therefore meaningless, and can actually result in image deterioration under certain circumstances.
Furthermore, the total amount of compression coded information increases and the effective compression ratio therefore decreases when in-field or in-frame coding is extensively used.
SUMMARY OF THE INVENTION
The present invention is a signal processing method and recording and reproducing means which digitize an image signal and code the digitized signal by singular or plural in-field, in-frame, inter-field, and inter-frame means. The inter-field or inter-frame coding means is the primary coding device. In-field or in-frame coding is applied at a regular interval to the inter-field or inter-frame coded signal sequence, scene changes are detected and in-field or in-frame coding is mandatorily applied to the field or frame immediately following the scene change, and this field or frame becomes the starting field or frame for the in-field or in-frame coding applied at a regular interval thereafter. The increased data quantity resulting from in-field or frame compression coding is thus compensated for by increasing the compression ratio of the inter-field or inter-frame compression coding means during the regular interval between in-field or frame coding.
The invention is further comprised to absorb the increase in information generated by the field or frame immediately after the scene change by mandatorily coding the field or frame immediately after a scene change by the in-field or in-frame coding means using the same data as that of the immediately preceding field or frame for the field or frame immediately before or after the scene change.
Thus, the field or frame immediately after the scene change is efficiently coded, and the total amount of information produced is not increased.
REFERENCES:
patent: 4694329 (1987-09-01), Belmares-Sarabia et al.
patent: 4837618 (1989-06-01), Hatori et al.
patent: 5049991 (1991-09-01), Niihara
patent: 5194961 (1993-03-01), Nagai
patent: 5223949 (1993-06-01), Honjo
Artieri, Alain and Colavin, Oswald, “A Chip Set Core for Image Compression,” IEEE on Consumer Electronics, vol. 36, No. 3, pp. 395-402 (Aug. 1990).
Matsushita Electric - Industrial Co., Ltd.
McDermott & Will & Emery
Vu Kim Yen
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