locate points in an image

NumberOfimages=4;       %chose the number of images you want to give input

srcFiles = dir('E:\frames12\*.png');  

for i = 1 : NumberOfimages

filename = strcat('E:\frames12\',srcFiles(i).name);

 I = imread(filename);  

 faceDetector = vision.CascadeObjectDetector();

fbox= step(faceDetector,I);

videoOutFace = insertObjectAnnotation(I,'rectangle',fbox,'Face');

%figure, imshow(videoOutFace), title('Detected face');

e=imcrop(I,fbox);

%figure,imshow(e);

imwrite(e,strcat('E:\frames13\',int2str(i),'.png'));

 imwrite(e,'acquired.jpg');

  a=imread('acquired.jpg');

I=rgb2gray(a);

%cornerDetector = vision.CornerDetector('Method','Minimum eigenvalue (Shi & Tomasi)','MaximumCornerCount',120);I = rgb2gray(a);

cornerDetector = vision.CornerDetector('Method','Local intensity comparison (Rosten & Drummond)','MaximumCornerCount',250);

pts = step(cornerDetector, I);

drawMarkers = vision.MarkerInserter('Shape','Plus','BorderColor','Custom','Size',2);

J = repmat(I,[1 1 3]);

J = step(drawMarkers, J, pts);

%imshow(J); title ('Corners detected in a grayscale image');

%imwrite(image,FullFileName,'png');

    imwrite(J,strcat('E:\frames12\frames\',int2str(i),'.png'));

end