A Study On Characteristics And Assessment For Mapping Algorithms Of RGBW Display

With the continuous pursuit of display technology which has high brightness, low power consumption and display color chromaticity accurately, as well as the rapid development of high resolution display panel, RGBW display technology has been one of the hot research direction in the world. RGBW technology based on the new sub-pixel layout which consists of red, green, blue and white sub-pixel. Convert rgb signal of traditional RGB monitor into RGBW signal of RGBW monitor through the signal mapping algorithm. Excellent signal mapping algorithm can bring the characteristics of high brightness and low power consumption, and can expand the range of display color space without color distortion. With the rapid progress of the theory of RGBW technology, the improvement of hardware production technology, the diversification of sub-pixel layout method and the upgrading of mapping algorithm. This technology has come into the stage of practical application. There are some manufacturers launched a variety of RGBW displays which have different characteristics.The display effect of RGBW display is largely depending on the specific conversion process of mapping algorithm and the compatibility between the mapping algorithm and sub-pixel layout. The ability of enhance luminance and color retention of algorithms is different, even the same algorithm will have separate display effect on unique sub-pixel layouts. So how to choose excellent algorithms from the existing mapping algorithms, and design an exceptional algorithm according to the specific sub-pixel layouts has become one of the hottest areas of RGBW technology research. As far as I know, there is no systematic objective assessment method which could effectively evaluate RGBW signal mapping algorithms, only a handful of subjective assessment for mapping algorithms. But subjective assessment is time-consuming, and difficult to analyze the essence of exceptional algorithm. The research about how the sub-pixel layout affects the performance of the display is not sufficient. All of these factors greatly affect the promotion of RGBW display. It has become one of the important problems needs to be solved rapidly in the display area.In the field of display, aggregative indicator is the most prominent point of the mapping algorithm evaluation, namely the corresponding RGBW image evaluation. Aggregative indicator is not a single indicator. so it is hard to establish an objective evaluation model. In this paper, based on the research of diverse sub-pixel layouts, make an intensive study of signal mapping algorithm assessment according to one of the sub-pixel layout.Specifically, in order to make the algorithm can be effectively compatible with different subpixel layouts, this paper introduces 4 kinds of representative sub-pixel layouts. Take the checkerboard layout for example, deeply analyzes the brightness and color space affected by this layout. This analysis method can be used for additional layouts. In the understanding of the effects caused by the unusual layout, it is not difficult to fine tune the mapping algorithm, in order to achieve a better display effect in monitors which have different sub-pixel layouts. In addition, this paper has carried out the actual measurement of RGBW display, which includes brightness, color space and some indicator related with display. The result showed that the RGBW display has the advantages in numerous aspects. This makes people have intuitive cognition of RGBW technology, and helpful to the targeted improvement of the algorithm.In order to put forward the aggregative indicator objective evaluation model of the mapping algorithm, I proposed three demands which should be satisfied by excellent mapping algorithm, and accordingly put forward the universal equation and brightness factor n which could be applied to select a good algorithm. Design simulation experiments which could evaluate the signal indicator of brightness and hue come from 7 kinds of algorithms. The result shows that the signal mapping algorithm which satisfies universal equation could be better able to maintain the hue and saturation, the signal mapping algorithm’s ability to enhance brightness is effectively characterized by brightness factor. In order to understand the relationship between the aggregative indicator and some signal indicators, I carried out the subjective evaluation experiments which assess algorithms according aggregative indicator and signal indicators. According to the result, analyze regression prediction model of aggregative indicator. Thus, the aggregative indicator objective evaluation can be divided into two steps, in the first place evaluate single indicator of mapping algorithms by universal equation and brightness factor and in the second place combined with the regression prediction model.The proposed universal equation, brightness factor and mapping algorithms objective evaluation method of aggregative indicator can be used for the research of existing mapping algorithm evaluation, and provide theoretical guidance for the new signal mapping algorithm. Meanwhile, the derivation process of universal equation has taken into account the specific subpixel layout and hardware parameters, so this equation can be used to modify existing mapping algorithm, making it compatible with displays which have different hardware parameters and sub-pixel layouts. Therefore, the research results of this paper have important guiding significance and practical application value, contributes the popularization of RGBW display technology.