基于Zernike多项式表示色域边界的色域映射

Gamut mapping based on gamut boundaries expressed with Zernike polynomials

在彩色图像的跨媒体复制中,由于不同媒体有不同的色域,所以在大多数情况下色域映射是不可避免的。不论采用何种映射算法,色域映射的第一步是确定有关媒体的色域边界。目前大多数的色域边界都是用一组测量的或用其它方法得到的离散数据来表示的。然而,由于这种表示方式是利用一组离散数据来实施色域映射的两个基本处理(即确定任一指定的等色调面平面中色域的边缘线以及确定色域边界与一条映射线的交点),比较复杂和费时,因此希望找到一种色域边界的解析表达式来解决这一问题。简述了不久前提出的一种解析函数色域边界表示方法,并用实例说明了如何利用这种解析表示(Zernike多项式)来实现上述的边缘线确定和交点确定。最后给出了几种映射算法的色域映射完整过程及其结果。

In crossmedia color image reproduction, gamut mapping is ineluctable in most cases due to gamut differences among different media. The first step of gamut mapping should be the determination of gamut boundaries of each medium, no matter what kind of mapping algorithm is to be used? The gamut boundary is mostly at present expressed with a set of discrete data which are measured or otherwise produced. Such an expression manner, however, is not an ideal one since it would take much storage space and make the determinations of boundary edges on an assigned equihue plane and of an intersection point between a boundary and a 'mapping line',two basic processes of gamut mapping, quite complicated and timeconsuming. So an analytical expression for the boundary is proposed by us recently. The emphasis is paid on showing by examples how to use that analytical expression, specifically a form of Zernike polynomials, to implement the said determinations of boundary edges and intersection points. Finally, the whole procedures of gamut mapping with several algorithms and their results are given. 