Image Coding Apparatus Using Motion-Based Weighted Prediction
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Solution Overview
Problem
Existing image coding techniques, such as those using the MPEG-4 AVC/H.264 standard, face challenges in maintaining image quality and coding efficiency while reducing computation and power consumption, particularly due to the inefficiencies in determining when to apply weighted prediction, which can degrade image quality and coding efficiency when not properly managed.
Innovation Solution
An image coding apparatus that determines whether to use weighted prediction based on whether an image is part of a picture group with significant motion, using imaging information to accurately assess motion and adjust the prediction method, thereby improving image quality and coding efficiency while reducing computation and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If weighted prediction is applied to all images, then coding efficiency for fading video is improved, but image quality deteriorates and computation amount increases
Solution Approach 1:
The patent applies different prediction methods to different pictures based on their characteristics. Specifically, weighted prediction is applied only to fading pictures where it is beneficial, while ordinary motion compensation is used for other pictures. This local differentiation resolves the contradiction by avoiding unnecessary computation and image quality degradation in pictures where weighted prediction is not appropriate, while still achieving improved coding efficiency where it is needed.
2Productivity
If weighted prediction is applied to all images, then coding efficiency is improved, but computation amount and power consumption increase
Solution Approach 1:
The patent determines whether each picture is a fading picture and applies weighted prediction only to those pictures where it is beneficial. By localizing the application of weighted prediction to only fading pictures rather than applying it universally, the system reduces unnecessary computation and power consumption in pictures where ordinary motion compensation suffices, while still achieving improved coding efficiency for fading content.
3Speed
If the determination method for fading pictures is simplified, then processing speed is improved, but determination accuracy decreases
Solution Approach 1:
The patent changes the parameters used for determining fading pictures from simple luminance value changes to motion vector-based determination. This parameter change allows for more accurate identification of fading pictures while maintaining efficient processing, as motion vectors are already computed during the motion compensation process. The patent thus improves determination accuracy without significantly impacting processing speed.
Data Source
AI summary
An image coding apparatus including an accumulating unit which accumulates a reference image, a predicted image generating unit which generates a predicted image of the current image to be coded by performing motion compensation with weighted prediction or motion compensation without the weighted prediction, and a coding unit which codes a difference between the predicted image generated by the predicted image generating unit and the current image to be coded. The image coding apparatus also includes a determining unit which determines whether or not the current image to be coded is included in a picture group which is a group of successive pictures and indicates motion equal to or larger than a predetermined amount of motion and which generates the predicted image by performing the motion compensation with the weighted prediction when it is determined that the current image to be coded is not included in the picture group.