我想选择图片中的一个长方形，可是这个长方形是斜的，请问怎么实现呀？
或者指导一下怎么得到它的四个顶点也可以，我用cpselect实现时，怎么点击四下，可是得到的却是两个值，也就是说显示的是一个点，请高手指点，急求！！！！谢谢

用getrect（）函数看看行吗！
GETRECT Select rectangle with mouse.
RECT = GETRECT(FIG) lets you select a rectangle in the
current axes of figure FIG using the mouse. Use the mouse to
click and drag the desired rectangle. RECT is a four-element
vector with the form [xmin ymin width height]. To constrain
the rectangle to be a square, use a shift- or right-click to
begin the drag.

RECT = GETRECT(AX) lets you select a rectangle in the axes
specified by the handle AX.

See also GETLINE, GETPTS.

x=ginput(4)