Contrast Enhancement for Emissive Display Using Histogram Equalization and Bilateral Tone Adjustment

Contrast enhancement has an important role in image processing applications. Conventional contrast enhancement techniques often fail to produce satisfactory results for broad variety of low contrast images or cannot be automatically applied to different images, because their parameters must be specified manually to produce a satisfactory result for a given image. A Power Constrained Contrast Enhancement algorithm for emissive displays based on histogram equalization (HE) and Bilateral Tone Adjustment Technique is proposed in this paper. For PCCE algorithm a log based histogram modification scheme which reduces the overstretching artifacts of the conventional HE technique is proposed. Then a powerconsumption model for emissive displays was developed and an objective function consisting of histogram equalizing term and the power term was formulated. By minimizing the objective function based on the convex optimization theory its found that the proposed algorithm achieves contrast enhancement and power saving simultaneously. Then the bilateral tone adjustment technique is used to improve the image quality. BiTA is applied to the luminance, while the color saliency detector calculates the amount of saliency of each pixel with respect to neighbourhood. Saliency produces a saliency map with well defined boundary of salient object. Regions with higher saliency values indicate that the regions have a higher extent of human interest deserve a greater degree of enhancement. Saliency Weighted Contrast Enhancement is then performed based on the adjusted luminance and saliency. The Simulation results demonstrate that the Bilateral Tone Adjustment Technique can reduce power consumption significantly while improving image contrast and perceptual quality.