Approximate computing is a novel approach to design area-efficient arithmetic units for portable error resilient applications. In this work, the authors have proposed a parallel architecture for median filter targeting digital image processing. Proposed parallel median filter (PMF) uses pre-sorter and post-merge units to replace corrupted processing pixel (PP) with a median of pixels in the 3X3 processing window. Approximate compare and swap (CS) blocks that can trade off area at the expense of accuracy are proposed and used in the proposed PMF. Two variants of PMF are realised based on the implementation of approximate CS units in the pre-sorter and post-merge blocks. In PMF-design1, the authors use the exact CS unit in the pre-sorter and approximate CS unit in the post-merge block (hereafter referred to as P-EA) and in PMF-design2, they use approximate CS unit in both pre-sorter and post-merge blocks (hereafter referred to as P-AA). Functionality and accuracy efficacy of the proposed PMFs are verified with the image de-noising application. Synthesis with 90 nm application specific integrated chip technology revealed that to the least, proposed PMFs demonstrate 33.75 and 41.9% area-delay product and power-delay product reductions, respectively, compared to the standard median filter.

中文翻译：

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使用近似比较器和忠实加法器的高效区域并行中值滤波器

近似计算是一种新颖的方法，可为便携式防错应用设计面积有效的算术单元。在这项工作中，作者提出了一种并行架构，用于针对数字图像处理的中值滤波器。提议的并行中值滤波器（PMF）使用预分选器和合并后单元将损坏的处理像素（PP）替换为3X3处理窗口中的像素中值。提出了可在牺牲精度的情况下折衷使用的近似比较和交换（CS）块，并在提议的PMF中使用。基于在预分类器和合并后块中实现近似CS单元，可以实现PMF的两种变体。在PMF-design1中，作者在预分选器中使用精确的CS单位，在合并后块（以下称为P-EA）和PMF-design2中使用近似的CS单位，它们在预分类器和合并后的块（以下称为P-AA）中均使用近似CS单位。所提出的PMF的功能和精度功效已通过图像降噪应用得到了验证。使用90 nm专用集成芯片技术进行的合成显示，与标准的中值滤波器相比，建议的PMF至少显示出33.75和41.9％的面积延迟积和功率延迟积减少。