Image analysis – Image compression or coding – Shape – icon – or feature-based compression
Reexamination Certificate
1998-08-03
2001-06-12
Couso, Jose L. (Department: 2721)
Image analysis
Image compression or coding
Shape, icon, or feature-based compression
Reexamination Certificate
active
06246799
ABSTRACT:
TECHNICAL FIELD
This invention relates to a picture compression encoding apparatus and a picture compression encoding method for compression-encoding picture data.
BACKGROUND ART
In recent years, with realization of image in digital form and progress of picture compression technology, various picture compression encoding processing have been carried out. However, in the prior art, code quantity allocated to picture data of a predetermined unit is fixed to a certain fixed quantity (in the case of the fixed rate), or even in the case of a variable rate to vary code quantity allocated to picture data of a predetermined unit in dependency upon fineness of picture, code quantity allocated at the maximum has been already determined. Therefore, the maximum value of code quantity within a predetermined time is determined. As a result, when continuous complicated pictures are successive, there was limitation in the code quantity. As a matter of course, increase or decrease of code quantity allocated to the picture leads to degree of the picture quality. In view of the above, in the prior art, it has been carried out to control code quantity so that the picture quality deterioration at the time of decoding becomes minimum while taking the same code quantity as the entirety of a single picture by a method of allocating a larger code quantity to complicated portions on the picture, etc.
However, way of sensing of the picture quality deterioration of viewer (viewer/listener) is changed to what portion attention is drawn within one picture. On the other hand, the portion that the viewer carefully observes is the portion important within that picture, and that portion is not limited to the complicated portion within that picture. For this reason, with the method of allocating a larger code quantity to the complicated portion on picture, inconvenience as described below takes place. Namely, in the case where, e.g., the main person exists within the complicated background, etc., larger codes are allocated to the complicated background. As a result, the code quantity allocated to the main person that the viewer carefully observes is less. Thus, the viewer feels picture quality deterioration at the time of decoding.
To cope with this, it is conceivable that the operator is permitted to arbitrarily change, every picture, allocation of code quantity within the picture. However, it is necessary to take much labor in order to allow the operator to set area different in allocation of code quantity, and in situations where real time characteristic such as live broadcasting, etc. is required, such an operation is impossible.
Meanwhile, in the Japanese Patent Application Laid Open No. 44110/1995 publication, there is disclosed the technology in which position of visual point of user is detected to display a predetermined area in the vicinity of the visual point position within one picture by high resolution, and to display other area by low resolution. In other words, it can be said that this technology is the technology in which code quantity allocated to the area in the vicinity of the visual point position within one picture is increased and code quantity allocated to other area is decreased. In accordance with this technology, picture quality deterioration that the user feels at the time of decoding can be suppressed while encoding respective pictures on the real time basis within a limited code quantity.
However, in the case where such an approach is always employed to increase code quantity allocated to the area in the vicinity of the visual point and to decrease code quantity allocated to other area, even if other area is not so complicated and code quantity to be allocated is not decreased, even in the case where quantity of codes generated is not so many, i.e., there is margin in the code quantity, there is the problem that quantity of codes allocated to other area is necessarily reduced and the picture quality of other area is unnecessarily deteriorated.
Moreover, the size of the area that the viewer carefully observes within picture is not limited to fixed size. Accordingly, in the case where the size of the area where quantity of codes allocated is increased is caused to be fixed (constant), problems as described below takes place. Namely, in the case where the area that the viewer carefully observes is larger than the area where code quantity is increased, larger code quantity is allocated in the area of the center side of the area that the viewer carefully observes so that there results small deterioration of the picture quality. In the area of the peripheral side of the area where the viewer carefully observes, code quantity to be allocated becomes small. As a result, deterioration of the picture quality becomes large. Thus, there results picture difficult to see for the viewer, i.e., picture of which picture quality has been deteriorated. To the contrary, in the case where the area where the viewer carefully observes is smaller than the area where the code quantity is increased, a large code quantity would be allocated also to the area except for the area where the viewer carefully observes. As a result, there may take place circumstances where code quantity allocated to the area where the viewer carefully observes becomes small.
This invention has been made in view of the problems as described above, and its object is to provide a picture compression encoding apparatus and a picture compression encoding method which are capable of compression-encoding picture data on the real time basis within a limited code quantity, and is permitted to obtain picture (image) having high picture quality from a viewpoint of visual sense for user as far as possible at the time of decoding.
DISCLOSURE OF THE INVENTION
A picture compression encoding apparatus of this invention comprises: encoding means for compression-encoding input picture data; visual point position detecting means for detecting visual point position on a picture based on the input picture data; area setting means for setting a visual point position vicinity area in the vicinity of a visual point position detected by the visual point position detecting means; and code quantity limiting means such that when code quantity generated by the encoding means is above a predetermined quantity, it limits code quantity generated by the encoding means so that code quantity allocated to the area except for the visual point position vicinity area set by the area setting means is smaller than code quantity allocated to the visual point position vicinity area.
In such a configuration, visual point position of operator on picture based on input picture data is detected by the visual point position detecting means, and visual point position vicinity area is set in the vicinity of the visual point position detected by the visual point position detecting means on the picture based on the input picture data. Moreover, input picture data is compression-encoded by the encoding means, and code quantity generated by the encoding means is limited by the code quantity limiting means by varying allocation of code quantity in dependency upon the area so that code quantity allocated to the area except for the visual point position vicinity area set by the area setting means is smaller than code quantity allocated to the visual point position vicinity area only when code quantity per predetermined time generated by the encoding means is above a predetermined quantity in the case where code quantity is not limited. Accordingly, when there is margin in the code quantity, there is no possibility that the picture quality may be unnecessarily deteriorated. Thus, there are provided the effects/advantages that picture data can be compression-encoded on the real time basis within a limited code quantity and there can be obtained picture (image) having high picture quality from a viewpoint of visual sense for user as far as possible at the time of decoding.
Further, a picture compression encoding apparatus of this invention comprises: encoding means for compression-encoding
Couso Jose L.
Frommer William S.
Frommer Lawrence & Haug LLP.
Simon Darren M.
Sony Corporation
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