Image processing using approximate datapath units

In this paper we present approximate adders and multipliers to reduce the datapath complexity of image processing systems with only a small degradation in PSNR performance. We build upon the approximate circuits proposed in [8] and [9]. We show that selective application of accurate and approximate adders can significantly improve the accuracy of a 2D DCT system. For instance, our implementation of 2D DCT has comparable PSNR performance compared to [8] with 34-50% reduction in area. We also propose an approximate multiplier where the partial products have varying degrees of approximation. Such a multiplier helps improve the accuracy of the system as demonstrated through FFT and Gaussian filter case studies.