Border-Aligned Basis Functions for Image Compression
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Solution Overview
Problem
Traditional lossy image compression techniques, such as JPEG, often introduce ringing artefacts due to sharp transitions in images, which can degrade image quality and require additional bits to suppress, thereby increasing data size and reducing compression efficiency.
Innovation Solution
The method involves selecting a set of basis functions based on the shape that crosses an image block, such as a line or border, to transform the block into a transform domain, reducing non-zero coefficients and bits required for encoding, thereby minimizing ringing artefacts without degrading image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional lossy compression techniques are used to reduce data size, then compression efficiency is improved, but ringing artefacts increase and image quality degrades
Solution Approach 1:
The patent applies local quality by selecting different basis functions for different regions of the image based on the presence and characteristics of borders. Instead of using a uniform compression approach across the entire image, the method identifies border regions and applies specialized basis functions (such as those aligned with border orientations) specifically to those regions, while using standard basis functions in other areas. This localized adaptation reduces ringing artefacts at borders while maintaining compression efficiency in border-free regions.
2Quantity of substance
If higher compression levels are applied to reduce data size, then compression ratio is improved, but observable ringing artefacts increase
Solution Approach 1:
The patent employs parameter changes by dynamically selecting basis functions based on border detection parameters. The system analyzes image characteristics (such as border orientation and location) and adjusts the transformation parameters accordingly. By changing the basis function parameters to match border characteristics, the method effectively reduces ringing artefacts even at higher compression levels, allowing for greater data size reduction without proportionally increasing observable artefacts.
3Object-affected harmful factors
If border-aligned basis functions are used to minimize ringing artefacts, then image quality is improved, but encoding complexity increases due to shape partitioning
Solution Approach 1:
The patent applies segmentation by dividing the image into distinct regions based on detected borders or shapes. Each segmented region is then processed with appropriately aligned basis functions. This segmentation approach systematically manages the complexity by breaking down the image processing task into smaller, more manageable segments, each with its own optimized basis function set, thereby reducing overall encoding complexity while maintaining image quality.
Solution Approach 2:
The patent uses preliminary action by performing border detection and basis function selection before the actual compression transformation. The system pre-identifies border locations and orientations, and pre-selects appropriate basis functions for each region. This preliminary preparation simplifies the subsequent compression process by avoiding complex real-time calculations during encoding, thus reducing encoding complexity while still achieving artefact reduction.
Data Source
AI summary
A method for encoding a block of a frame. The method includes receiving the block that is in the spatial domain; selecting, based on a border that crosses the block, a set of basis functions for transforming the block to a transform domain; transforming the block using the set of basis functions to obtain a transform block; encoding, in a compressed bitstream, an indication of the set of basis functions; and encoding, in the compressed bitstream, the transform block.