Visual effects such as shadows and highlights appear in photographs due to variations in lighting conditions. Although these effects add more meaning to the images, they pose various problems to specific computer vision algorithms. Hence, the removal of shadows and highlights is often considered as a prerequisite to such algorithms. This paper presents an interactive technique for shadow elimination from images. Our method requires user input in the form of rough strokes on the shadow region and its corresponding non-shadow region in the image. We further use quaternion rotation in the YCbCr color space to derive an image that is invariant to shadows. The actual colors of the image are finally recovered by color transfer from the original shadow image. The proposed method takes less time to generate the shadow-free image and does not necessitate the detection of shadows prior to its removal. Also, unlike the existing shadow-removal techniques, our method generates invariant image with minor texture loss. Experimental findings are reported to demonstrate the performance of our shadow-removal technique.

由于光线条件的变化，照片中会出现阴影和高光之类的视觉效果。尽管这些效果为图像添加了更多含义，但它们给特定的计算机视觉算法带来了各种问题。因此，阴影和高光的去除通常被认为是这种算法的先决条件。本文提出了一种从图像中消除阴影的交互式技术。我们的方法要求用户在图像的阴影区域及其对应的非阴影区域上以粗笔画的形式输入。我们进一步在YCbCr颜色空间中使用四元数旋转来得出不变于阴影的图像。图像的实际颜色最终通过颜色转移从原始阴影图像中恢复。所提出的方法花费更少的时间来生成无阴影图像，并且不需要在去除阴影之前对其进行检测。而且，与现有的阴影去除技术不同，我们的方法生成具有少量纹理损失的不变图像。据报道，实验结果证明了我们的阴影去除技术的性能。