Picture coding apparatus, and picture coding method
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorsHideki Inomata, Okikazu Tanno, Tokumichi Murakami
Life of this patent
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Abstract
A picture analyzer detects coding difficulty information by analyzing the source picture data. A picture converter converts the format of the source picture data using spatial conversion or temporal conversion, or both. A coding unit then codes the converted picture data output from the picture converter. A preprocess controller controls the picture converter based on the coding difficulty information, selecting either spatial conversion or temporal conversion, or both. The resulting encoded picture features visually outstanding image quality in which block distortion is not conspicuous, and the coding unit avoids using a coarser than necessary quantization step even when the bit rate is low.
Claims27
A picture coding apparatus comprising:
- a picture analyzing unit for analyzing source picture data to obtain coding difficulty information;
- a picture conversion unit for converting a picture format of the source picture data;
- an coding unit for encoding picture data converted by the picture conversion unit;
- and
- a conversion controller for controlling the picture conversion unit based on the coding difficulty information to convert the picture format using spatial conversion, temporal conversion, or both.
A picture coding apparatus comprising:
- a picture area dividing unit for dividing a screen of source picture data into a plurality of areas;
- a prefilter for preprocessing the source picture data;
- a coding unit for coding the source picture data preprocessed by the prefilter;
- and
- a filter control unit for controlling a prefilter characteristic by picture area.
A picture coding apparatus comprising;
- a picture area dividing unit for dividing a screen of source picture data into a plurality of areas;
- a coding parameter calculating unit for calculating a coding parameter by picture area;
- and
- a coding unit for coding the source picture data by switching the coding parameter by picture area.
A picture coding apparatus comprising;
- a preprocessing unit for preprocessing source picture data;
- a coding unit for coding source picture data output from the preprocessing unit, and then locally decoding the coded source picture data;
- and
- a preprocessing controller for obtaining a difference between the source picture data and locally decoded data output from the coding unit, and controlling the preprocessing unit based on this difference data.
A picture coding method for coding source picture data after picture conversion, comprising a step for:
- converting a picture data format based on coding difficulty information using spatial conversion, temporal conversion, or both.
A picture coding method for coding source picture data after preprocessing the source picture data through a prefilter, comprising a step for:
- dividing a screen of source picture data into a plurality of areas;
- and
- changing a filter characteristic of the prefilter by picture area to preprocess the source picture data.
A picture coding method for coding source picture data, comprising a step for:
- dividing a screen of source picture data into a plurality of areas;
- and
- coding the source picture data by switching the coding parameter by picture area.
A picture coding method comprising a step for:
- obtaining a difference between the source picture data and locally decoded data that is source picture data coded and then locally decoded;
- and
- controlling preprocessing source picture data based on the resulting difference data.
Dependencies are inferred from the claim text.