Normally, the 2D scatter plot like this
http://s14.sinaimg.cn/mid...k6hzy6O40b3o5v4d&690 (Open the link, you can see the scatter plot figure). The points appear dense and dark in the figure. However, in other case, they appear sparse and faint, like this
http://s5.sinaimg.cn/midd...k6hzy6O40aZBU8e4&690 (Open the link, you can see the scatter plot figure). How to change the style from one to the other? Many thanks!