Study of Energy Efficient Images with Just Noticeable Difference Threshold Based on Feature Transform

Abstract

A novel method is presented for producing energy-efficient images, i.e., images that consume less electrical energy on energy-adaptive displays, yet have the same, or very similar perceptual quality to their original images. The proposed method relies on the fact the energy consumption of pixels in modern energyadaptive displays like OLED displays are directly proportional to the luminance of the pixels. Hence, in this work to reduce the energy consumption of an image while at the same time preserving its perceptual quality, it is proposed to reduce the luminance of the pixels in the image by one just-noticeable-difference (JND) threshold. To determine the JND thresholds, a Feature Transform based just Noticeable Difference Threshold (FTJNDT) model is developed. In the proposed model, the JND thresholds of each block in the given image are elevated by two non-linear saliency modulation functions using the visual saliency of the block. The parameters of the saliency modulation functions and obtain feature value are estimated through an adaptive optimization framework, which utilizes a state-of-the-art saliency-based objective image quality assessment (IQA) method. To evaluate the proposed methods, a set of subjective experiments were conducted, and the real energy consumption of the produced energy-efficient images were measured by accurate power monitor equipment on an OLED display. The obtained experimental results demonstrated that, on average, the proposed method is able to reduce the energy consumption by about 4.31% while preserving the perceptual quality of the displayed images.