Correcting veiling glare of refined CIECAM02 for mobile display

Abstract

Small displays are widely used; they are small enough to be carried around and are often viewed under extreme surround conditions. Under bright illumination, mobile display users experience ''veiling glare'' caused by bright ambient lighting. A refined version of CIE-CAM02 called ''Refined CIECAM02 and original CIE-CAM02'' were tested to predict visual results in terms of lightness (J), colourfulness (M), and brightness (Q) on a 2-inch sized display (2 00 ) mobile phone under four surround conditions; dark (0 cd/m 2 ), dim (5 cd/m 2 ), average (1000 cd/m 2 ), and bright (10,000 cd/m 2 ). Other than the two versions of CIECAM02 using the original data, a correction to the models' predicted lightness J and a black correction to the original data were developed. Overall, the refined CIECAM02 plus the J correction performed the best for predicting the lightness, brightness and colourfulness under all the viewing conditions, especially for bright surround condition. Furthermore, another experiment was carried out using complex images to verify different versions of CIECAM02. The images were reproduced using JMh (lightness, colourfulness, and hue) spaces from the modified CIECAM02 versions. The experiment was conducted by comparing original images viewed under dim, average, or bright surround conditions and the predicted images were viewed under dark surround condition on two identical mobile displays. The different versions of the CIECAM02 showed similar results to each other for dim and average surround conditions but large differences when predicting the images under bright surround condition. The refined CIECAM02 with the J 0 formula performed the best amongst all four CIECAM02 versions.

Improving color reproduction accuracy of an OLED‐based mobile display

“…This approach was indeed used in a number of previous studies on mobile displays . ‐ However, the CIECAM02 has been shown to be less useful for predicting the performance of mobile displays subjected to a wide variety of illumination conditions . Also, even after refining the CIECAM02 model specifically for mobile displays the resulting color accuracy was shown to leave much room for improvement …”

A Perceived Contrast Compensation Method Adaptive to Surround Luminance Variation for Mobile Phones

“…CIECAM 97s [3] and CIECAM02 [4] color appearance models, developed by the Commission Internationale de L'Eclairage (CIE), determined the surround compensation ratios for average, dim, and dark levels. Various algorithms, such as illuminant adaptive color reproduction [1,5] and veiling glare correction [6] for mobile displays, have been proposed to solve this image quality degradation problem. Display adaptive tone mapping operators can also be used to minimize visible contrast distortions for mobile displays [7].…”