按照这个要求，对前面进行取样得到数据进行处理，并记录下使上式最小的那一对组合，就初步确定了最佳的取样点。

　　 其实，这个时候我们也就可以初步获得处理后的α值了，比如对于我们前面所说的Trimap，其原始图像及经过sample和gather处理后的结果如下图：(We are interested in a general alpha matting approach for the simultaneous extraction of multiple image layers; each layer may have disjoint segments for material matting not limited to foreground mattes typical of natural image matting. The estimated alphas also satisfy the summation constraint. Our approach does not assume the local color-line model, does not need sophisticated sampling strategies, and generalizes well to any color or feature space in any dimensions)