Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
2000-10-10
2003-11-18
Lee, Young (Department: 2613)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
Reexamination Certificate
active
06650708
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a video signal encoding apparatus for enlarging a video signal through a coding process.
BACKGROUND OF THE INVENTION
In encoding images, such situations frequently occur in which it is required to enlarge moving pictures. When an input moving picture is encoded after it is enlarged, we consider that the picture is first enlarged in a spatial domain and then encoded. In this case, such processes as discrete cosine transform (DCT) are performed subsequent to the enlargement of the picture. Accordingly, the volume of calculation required for encoding increases as compared with that where the image is not enlarged.
A video signal encoding apparatus capable of encoding an input moving picture after enlarging it, while avoiding the problem just described of increase in the volume of calculation, is disclosed in Japanese Non-examined Publication No. H10-308946. An example of the video signal encoding apparatus performing encoding after enlargement of an input moving picture is shown in FIG.
5
. This apparatus is described in the case of doubling an input picture in the vertical direction.
Block converter
502
divides input image
501
into 8×4 blocks formed of eight horizontal pixels and four vertical lines. Inter-frame prediction unit
503
performs inter-frame prediction with the use of the divided 8×4 blocks and reference picture generated by reference picture replacing unit
508
and generates 8×4 differential blocks and motion vectors. When inter-frame prediction is not performed, 8×4 blocks generated in block converter
502
comes to be 8×4 differential blocks.
Then, 8×4 DCT coefficient blocks are generated from 8×4 differential blocks by DCT unit
504
. Quantizer
505
quantizes 8×4 DCT coefficient blocks to generate 8×4 quantization coefficient blocks. Inverse quantizer
506
inverse-quantizes 8×4 quantization coefficient blocks to generate 8×4 inverse quantization coefficients blocks.
Further, inverse discrete cosine transform (IDCT) unit
508
performs IDCT processing on 8×4 inverse quantization coefficient blocks to generate 8×4 decoded blocks. Reference picture replacing unit
508
updates the reference picture with the use of 8×4 decoded blocks and motion vectors generated in inter-frame prediction unit
503
.
Vertical doubling unit
509
enlarges 8×4 quantization coefficient blocks, obtained through quantization processing, in a frequency domain to generate 8×8 quantization coefficient blocks. Thus, the size in the vertical direction of the block becomes double that of the input picture.
Variable length coding (VLC) unit
510
performs variable length coding processing on 8×8 quantization coefficient blocks to generate compressed data
511
.
By subjecting data first to DCT and quantization processing and then encoding the obtained data in a frequency domain as described in the above example, the amount of data calculation required for the picture coding is reduced from that where the input picture is first enlarged and then encoded.
In the example described above, the size of the block subjected to IDCT processing in the local decoder is 8×4. On the other hand, when a decoding apparatus, which has received the output of the compressed data from this apparatus, decodes the compressed data, IDCT processing is performed on 8×8 blocks as a unit. Namely, the size of the blocks subjected to IDCT processing in the former apparatus, i.e., the encoding apparatus for encoding an image, is different from the size of the blocks subjected to IDCT processing in the latter apparatus, the decoding apparatus receiving the encoded data and decoding the received data. Due to the difference in the size of blocks, errors occur in the frame subjected to the inter-frame predictive processing between the image encoded and the image decoded. Especially, errors accumulate at the edge portions of the image and this causes distortion of the image or color registration error.
SUMMARY OF THE INVENTION
The object of the present invention is the provision of a video signal encoding apparatus enlarging the image in a frequency domain when performing encoding of a motion picture thereby reducing the amount of data calculation required for the encoding and suppressing deterioration in image quality.
The video signal encoding apparatus of the present invention performs DCT calculation and quantization with the use of m×n block (m, n: natural number) as the unit block for coding a motion picture and, then, converting the block into s×t block (s, t: natural number, s≧m, t≧n), performs variable length coding. Thus, the apparatus generates compressed data of an enlarged motion picture and delivers the enlarged output.
In the local decoder of the apparatus, it is selected by a switcher whether m×n inverse quantization coefficients, obtained by inverse quantization, are to be decoded by an s×t IDCT unit or by an m×n IDCT unit, in accordance with the accuracy in motion compensation.
Further, the apparatus has a resizing unit for adjusting a motion-compensated reference picture to the picture size of an input image.
In another embodiment of the invention, the apparatus has the same configuration as that of the above described embodiment except that the local decoder in this apparatus decodes m×n inverse quantization coefficients, obtained by inverse quantization, in an s×t IDCT unit.
Having the described configuration, the video signal encoding apparatus performs the encoding by enlarging a motion picture in a frequency domain so that the amount of data calculation in the encoding is decreased and deterioration in picture quality is suppressed.
REFERENCES:
patent: 5845015 (1998-12-01), Martucci
patent: 5963673 (1999-10-01), Kodama et al.
patent: 6052415 (2000-04-01), Carr et al.
patent: 2 332 113 (1999-06-01), None
patent: 10-308946 (1998-11-01), None
A. Vetro et al. “Minimum Drift Architectures for 3-Layer Scalable DTV Decoding”, IEEE Transactions On Consumer Electronics, vol. 44, No. 3, Aug. 1998, pp. 527-536.
S. Martucci, “Image Resizing in the Discrete Cosine Transform Domain”, Proceedings of the International Conference on Image Processing, vol. 3, Oct. 23, 1995, pp. 244-247.
European Search Report corresponding to application No. EP 00 12 1291 dated Apr. 7, 2003.
Lee Young
Matsushita Electric - Industrial Co., Ltd.
RatnerPrestia
LandOfFree
Video signal encoding apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Video signal encoding apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Video signal encoding apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3155807