IMSHOW(x,y,A,...) uses the 2-element vectors x and y to<BR> establish a nondefault spatial coordinate system, by<BR> specifying the image XData and YData. Note that x and y can <BR> have more than 2 elements, but only the first and last <BR> elements are actually used.<BR>x,y为二元数组,确定横纵座标起始,也可以是多维,但只有起始和最终元素有效<BR>例如imshow([0.5,1],[0.3,1],onion)<BR>