Wavelet Transform Unit for DRAM-Free Image Encoding
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Solution Overview
Problem
Real-time image transmission systems require efficient image encoding without the use of DRAM buffers to reduce cost and complexity, as existing 2D wavelet image encoding algorithms are not feasible in DRAM-buffer-less scenarios, such as surveillance cameras with constant transmission rates.
Innovation Solution
An image encoding system employing a wavelet transform unit, scan unit, quantizer, and entropy coder, which performs 1D, dual-line-based, or four-line-based wavelet transforms, and adaptive quantization, using SRAM buffers to store data, allowing for efficient compression and transmission without a DRAM buffer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If 2D wavelet image encoding algorithm is used, then compression quality is improved, but device complexity and memory requirements increase due to DRAM buffer requirements
Solution Approach 1:
The patent segments the image processing into multiple passes, with each pass handling a specific sub-band or frequency component. This allows the complex 2D wavelet transform to be broken down into simpler 1D transforms that can be executed sequentially with minimal buffering, resolving the contradiction between compression quality and system complexity.
Solution Approach 2:
The patent performs preliminary sorting and reordering of wavelet coefficients before the main encoding process. By pre-organizing the data in a favorable order, the subsequent encoding requires less memory buffering and processing complexity, thereby maintaining compression quality while reducing device complexity.
2Manufacturing precision
If 2D wavelet image encoding algorithm is used, then compression quality is improved, but loss of time increases due to DRAM buffering requirements
Solution Approach 1:
The patent implements a continuous encoding process where the wavelet transform and encoding operations overlap in time. By using pipelining and keeping the encoder continuously busy with pre-processed data, the system achieves high compression quality without the time loss associated with DRAM buffering and data transfer.
3Productivity
If DRAM buffer is used, then encoding efficiency is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts and removes the DRAM buffer component from the system by implementing algorithms that operate with minimal or no external memory buffering. The encoding efficiency is maintained through careful data management and processing techniques that eliminate the need for large DRAM buffers, thereby reducing device complexity and cost.
4Loss of information
If tile-based coding with large tile size is used, then compression ratio is improved, but device complexity increases due to DRAM buffer requirements
Solution Approach 1:
The patent transitions from spatial-domain tiling to frequency-domain processing by applying wavelet transforms. This dimensional change allows the system to achieve high compression ratios through frequency-selective encoding without requiring large DRAM buffers for spatial tile management, thereby reducing device complexity while maintaining compression efficiency.
Data Source
AI summary
An image encoding system is disclosed. The image encoding system comprises a wavelet transform unit and a processing circuit. The wavelet transform unit performs a multiple-line-based wavelet transform on plural consecutive component lines to generate a wavelet transformed image comprising wavelet coefficients of plural sub-bands. The processing circuit coupled to the wavelet transform unit for quantizing, scanning and encoding the wavelet coefficients to generate a compressed image. Here, a number of the plural consecutive component lines is a multiple of 2 and less than 5. Since the wavelet transform unit performs the multiple-line-based wavelet transform to reduce the storage amount and maintain a good compression quality, an image encoding system of the invention can use SRAM buffers instead of a DRAM buffer.