Perceptually Optimal Reproduction of Color Images considering Device Limits

在拟议的项目中，应考虑到输出设备的限制（打印机、显示器和投影仪），研究多光谱、高动态范围图像的感知最佳再现。特别感兴趣的是有限的同色异谱和光谱色域以及这些设备的低动态范围。先前的方法仅集中于一个单个设备限制（色域映射、光谱色域映射和HDR色调映射）。然而，为了允许人类视觉系统的各种外观现象，统一的方法是必要的。为此，应修改现有的图像外观模型，以便将图像映射到感知上均匀的外观相关空间。该项目的一个基本目标是基于人类的空间和色彩视觉在该空间内开发图像差异测量。对于一个多光谱图像的耦合变分问题序列的设备的限制，可以通过这种图像的差异措施。解决方案是一个算子，它将图像转换为设备限制，与原始图像的感知差异最小。应发展新的数值方法来解决这些变分问题。应特别重视其数值复杂性、收敛速度和鲁棒性，以便在合理的时间内处理高分辨率多光谱图像。一个原型的多光谱再现系统的设计和实现，以显示这种方法的可行性，其适用性方面的计算性能，并验证其最优性的心理物理比较实验与现有的方法。

In the proposed project the perceptually optimal reproduction of multispectral, high dynamic range images shall be investigated considering output-device limits (printers, displays and projectors). Of special interest are the limited metameric and spectral gamut as well as the low dynamic range of these devices. Previous approaches focused only on one single device limit (gamut mapping, spectral gamut mapping and HDR tone mapping). To allow for various appearance phenomena of the human visual system, however, a unified approach is necessary. For this purpose existing image appearance models shall be modified in order to map the image into a perceptually uniform appearance correlate space. One basic goal of this project is the development of an image difference measure within this space based on human spatial and color vision. For a multispectral image a sequence of coupled variational problems subject to device limits can be constructed by means of this image difference measure. The solution is an operator, which transforms the image into the device limits with minimal perceptual disagreement to the original. New numerical methods shall be developed to solve these variational problems. Particular importance shall be attached to their numerical complexity, convergence speed and robustness in order to handle also high resolution multispectral images in reasonable time. A prototypical multispectral reproduction system shall be designed and realized to show the feasibility of this approach, its applicability in terms of computational performance and to validate its optimality by means of psychophysical comparison experiments with existing methods.