Multi-primary Color Display Device Color Reproduction Of Some Key Issues

With the development of semiconductor technology, Multi-primary display became one of the most important topics among display and thus has attracted great attention. MPD can give brighter color and a better vision. Therefore, it is also one of the technical trends in the future.After the extensive research has been done concerning multi-primary display, however, there are some problems coming out. The first one is the relationship between the color gamut and the luminance for MPD system. A full description of the color gamut for one display system should take the luminance into consideration. The relationship between the color gamut and the luminance for MPD system is different from the one for the traditional 3-primary display system. Some methods have already been proposed. But those methods can only describe the relationship for those display system whose primaries' color coordinates form a convex polygon. But in sequential display system, the primaries' color coordinates will form a concave polygon. So those methods can't solve such problems. The second one is about color space conversion. It is basically a matrix calculation and results in a great amount of calculation. So interpolation techniques are wildly used. It also introduces undesirable error which has troubled us several years. Scientists and engineers proceeded only with data analysis and computer simulation, not with theoretical study. So they can not explain the error distribution and its value. The last one is color temperature design for MPD. Because the increase of the primary number, it becomes quite different from the traditional 3-primary display system. The key is inversing a non-square form matrix. There are some ways. But they depend on the number of the primaries. They can't design the color temperature whose primary number is beyond their limitation.These three main issues in MPD are thoroughly studied in this thesis. Mang Ou-Yang's arithmetic is implemented as software. A new method describing the relationship between the color gamut and the luminance for DLP display system with SLR technology is proposed. The 3D interpolation technology, which is widely used in display, is analyzed by using Taylor's theorem. A new tetrahedral interpolation method is proposed based on the Taylor polynomial. The ripple error is also studied. A new method for color temperature design in MPD system is presented.This thesis concerns the theoretical study, arithmetic optimizing, computer aid solving, software simulation, experimental discussion and data analysis. Considerable progress has been made.Firstly, the relationship between the color gamut and the luminance for MPD system is researched in this thesis. By studying the methods presented by predecessor, it is found that those methods can not describe the relationship for such a type of display system, whose primaries form a concave polygon on the xy chromaticity diagram. A new method is presented: According to the display system, disassembling the primary, and calculating the numerical value with the aid of computer. It can solve the problem which can not be solved by the previous methods. The Digital Light Processing (DLP) display system with Spoke Light Recapture (SLR) is a classic one of such display system. Experiment results show that this method can describe the relationship of the color gamut and the luminance of DLP display system with SLR very well.Secondly, the interpolation technology is studied by using Taylor's theorem and from a mathematical way. It is found that the structure of tetrahedral interpolation formula is similar to the structure of Taylor polynomial. It is also found that some of the errors come from the first item of the interpolation formula. This reveals the source of the error and gives a theoretical error limitation of linear interpolation. According to this, the original tetrahedral linear interpolation method is improved by modifying its first item according to the luminance. A new tetrahedral interpolation method is also proposed based on the Taylor polynomial. The error of this new method is reduced to 91%-97%. And its computation cost is less than the original one.Lastly, based on the progresses, a new method for color temperature design in MPD system is presented. Essentially, the problem of color temperature design is matrix inversion. For MPD, the coefficient matrix is not in a square form, which always yields an infinite solution set. The new method uses nonlinear programming. The constraints and the objective function are designed in the way of nonlinear programming. Different objective functions reflect different goals. For DLP front projector, which are always used in an environment with natural daylight background, the summation of the luminance of each light source are chosen to be the objective function and maximize it. Experiment results are satisfactory. Because this method is not for one specific type of display system, it can be widely used.