Continuous tone: A image in which tonalgradation is produced by gradually changes of density.
连续色调：由渐变密度构成的不同色调层次的图像。
The outer rectangular bounds and tonal-gradation information are employed to be eigenvectors to match respective targets, so as to get the speed of them.
利用最小外接矩形和灰度信息作为各目标的特征向量，匹配各目标对象，以求取各目标运动速度。
A master of tonalgradation and soft edges, he prepared the way for the Impressionist landscape painters and had an important influence on Claude Monet, Camille Pissarro, and Berthe Morisot.