基于宽色域显示的色域扩展映射研究

发布时间：2018-06-24 19:40

本文选题：色域扩展映射 + 肤色保护　；参考：《山东大学》2015年硕士论文

【摘要】：随着宽色域显示设备的迅速发展,具有高饱和度、高亮度、高清晰度的激光显示越来越受到重视,逐渐成为显示领域研究的重点。激光显示色域的颜色覆盖率与NTSC制式相比,达到了1.8倍,与PAL制式相比,达到了1.9倍以上。但由于激光色域和现有制式标准并不匹配,颜色信号不能直接在激光显示设备中显示,否则会造成传输信号的失真。因此,在激光显示中对颜色进行空间转换和色域的扩展映射成为必不可缺少的步骤,以充分展现宽色域显示的高饱和度高亮度的优势,因而研究出一组适用的色域扩展映射算法显得尤为重要。随着色域扩展映射研究的进一步深入,在扩展映射过程中很容易忽略肤色的处理,这就容易产生过度渲染和肤色与发色混乱等问题,毁坏了原有图像的肤色分布。本文针对这一问题,主要研究了色域扩展映射过程中的肤色保护算法。论文首先对色域扩展映射的基本理论包括原理和研究方法进行了详细介绍,其次介绍了现有的肤色模型,并对其进行比较对比,选出本文所用的模型,在此基础之上,深入研究了色域扩展映射过程中的肤色保护算法。本文提出的两种色域扩展映射过程中对肤色进行保护的算法分别是：变色调肤色保护算法和基于概率模型的肤色保护算法。变色调肤色保护方法是针对了不同的色调,将现有的扩展映射算法结合起来,在拉伸的过程中,通过调整角度使得扩展映射在线性与非线性之间转换,最终达到颜色变化平缓无色块,但保证不了在肤色边界区域处的肤色点值没有变化,以及当脸上肤色与发色接近时,无法很好的保护肤色。基于概率模型的肤色保护算法是在进行扩展之前先判定肤色区域,当脸上肤色与发色接近时,求取能量最小值以确定肤色区域的边界,对于非肤色部分进行正常的扩展,对于肤色部分进行较小系数的扩展,保证扩展之后肤色自然。通过对大量图片进行色域扩展映射实验,表明上述肤色保护算法有效,不仅消除过度渲染问题,还能准确的对肤色进行扩展映射,有较好的扩展效果。
[Abstract]:With the rapid development of wide color gamut display devices, laser display with high saturation, high brightness and high definition has been paid more and more attention, and has gradually become the focus of research in the field of display. Compared with NTSC, the color coverage of laser display gamut is 1.8 times and 1.9 times higher than that of pal. However, because the laser color gamut does not match with the existing standard, the color signal can not be displayed directly in the laser display device, otherwise it will cause distortion of the transmission signal. Therefore, space conversion and color gamut mapping in laser display are indispensable steps to fully demonstrate the advantages of high saturation and high brightness in wide color gamut display. Therefore, it is very important to develop a set of suitable color gamut extension mapping algorithms. With the further study of color gamut extension mapping, it is easy to ignore the skin color processing in the process of color expansion mapping, which can easily cause problems such as excessive rendering and color confusion, and destroy the skin color distribution of the original image. In order to solve this problem, this paper mainly studies the skin color protection algorithm in the process of color gamut extension mapping. Firstly, the basic theory of color gamut extension mapping is introduced in detail, then the existing skin color model is introduced and compared, then the model used in this paper is selected. The skin color protection algorithm in the process of color gamut extension mapping is studied in detail. In this paper, we propose two algorithms to protect skin color in the process of color gamut extension mapping: changing tone skin color protection algorithm and color protection algorithm based on probabilistic model. The method of changing tone skin color is to combine the existing extended mapping algorithms for different hue. In the process of stretching, the extended mapping is transformed between linear and nonlinear by adjusting the angle. Finally, the color change is smooth, but it can not guarantee the change of the color point in the skin boundary area, and when the color of the face is close to the hair color, it can not protect the skin color very well. The probabilistic model based skin color protection algorithm is to determine the skin color area before the expansion. When the skin color is close to the hair color, the minimum energy is obtained to determine the boundary of the skin color area, and the normal expansion of the non-color part is carried out. For the skin part of the expansion of a small coefficient to ensure the expansion of natural skin color. Experiments on color gamut mapping of a large number of images show that the above skin color protection algorithm is effective, not only to eliminate the over-rendering problem, but also to accurately map the skin color, which has a good expansion effect.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TP391.41;TN27

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