A Modified Sliding Window Architecture for Efficient BRAM Resource Utilization

Sliding window is one of the most commonly used techniques in image processing algorithms. Implementing it in hardware requires buffering image rows on-chip to exploit data locality and avoid redundant off-chip pixel transfers. However, scaling this architecture to large window sizes or high resolutions linearly increases on-chip memory utilization. This imposes limitations on porting many image processing algorithms into hardware efficiently. In this paper, we propose a new sliding window architecture that utilizes less on-chip memory resources while maintaining performance as compared to the traditional method. The proposed architecture exploits that most natural images have smooth color variations with fine details in between these variations to compress images. It decomposes non-zero image pixels into their wavelet components and represents each wavelet coefficient with a minimum number of bits. The architecture is also flexible to use lossless or lossy compression based on a configurable threshold value. The FPGA implementation of our proposed architecture shows memory saving of 25-70% compared to the traditional architecture using lossless compression, and for lossy compression with up to a mean square error of 5 achieves up to 84% in memory savings.