A comparative study of focused Jpeg compression, FJpeg

Abstract

Eye movements are one important component of human vision: only specific regions of the visual scene are fixated and processed by the brain at high resolution. The rest of the image is sampled at lower and coarser resolution by the retina; but still, the image is perceived as uniformly clear. A focused Jpeg encoder, FJpeg, or visual-compression has been developed to operate in a similar fashion. Its implementation is based on specific image processing algorithms capable of predicting human regions-of-interest, ROIs, and on a corresponding differentiated quantization of the DCT coefficients. With FJpeg, the fidelity of ROIs are maintained by preserving their Jpeg–DCT frequency coefficients and balancing this by strongly compressing the residual part of an image, peripheral to the ROIs. It is possible in this way to increase the average compression ratio while preserving visual quality of the image. We present carefully designed experiments to demonstrate that subjects judged FJpeg visual-compression images as superior to standard Jpeg images over a number of conditions.