Content-Based LCD Backlight Power Reduction With Image Contrast Enhancement Using Histogram Analysis

Abstract

In recent years, low-power technology has had a significant impact on portable electronic devices; with mobile devices, the low-power circuit design has become the primary issue. At present, thin-film transistor liquid crystal display (TFT LCD) is widely used in handheld mobile devices. In terms of the overall system power consumption, TFT LCD power consumes 20%-45% of total system power due to different applications. The backlight of an LCD display dominates the power consumption of the whole system; controlling the backlight current to reduce the brightness and the contrast of LCDs can reduce the overall power consumption. However, this may cause significant changes in visual perception. In order to reduce the power consumption and eliminate the visual changes, the issue becomes: how to reduce the current by adjusting brightness and contrast in accordance with the current image. Based on content analysis, this paper proposes two new algorithms: the new backlight-dimming algorithm (NBDA) and the new image enhancement algorithm (NIEA). The proposed methods can, on average, simultaneously reduce power consumption by 47% and improve the image enhancement ratio by 6.8%. Moreover, the structural-similarity index metric (SSIM) is used to evaluate image quality.