ishghandle True for Handle Graphics object handles.
    ishghandle(H) returns an array that contains 1's where the elements
    of H are valid graphic object handles and 0's where they are not.
    Differs from ISHANDLE in that Simulink objects handles return false
% 判断H是否是图像句柄，如：
I = imread('000.jpg'); H = imshow(I);
ishghandle(H)
ans =
     1
A = 666.6471;
>> ishghandle(A)
ans =
     0