smart ginput or getpts : how to unselect a point

I need a GUI for selecting many points in an image. I want Matlab to delete a previously selected point if I click it again, or click on it with the right mouse button (not just the last point I selected, but any of the previous points!). how do I do this? tnx

Answer 1

[Vinny Chandran Suja]

As ImageAnalyst said there is no inbuild feature in ginput that supports your requirement. However, I came up with the following workaround:

(a) Query single points from ginput in a loop

(b) [For selecting points] If the input was from a left click, add the data to an array/structure

(c) [For removing points] If the input was from a right click, query the nearest neighbor from the array/structure and remove it from the dataset.

A minimal example is below for:

while(1) 
[Imx, Imy , mb]=ginput(1);

    if mb==1 
    data(:,count)=[Imx,Imy];
    % optionally display points
    handlesPointsInImage(:,count)=plot(Imx,Imy,'.r');
    end

    if mb==3
     ind=knnsearch(data(1:2,:)',[Imx,Imy]);
     data(:,ind)=[];
     % if points were displayed
     delete(handlesPointsInImage(:,ind));
     handlesPointsInImage(:,ind)=[];
    end

    if mb==2 % Middle mouse button exits the pick mode
     break;
    end 
   count = count +1;
end

Answer 2

[Image Analyst]

I don't think there is a way for ginput(), but for getpts(), the help says: "Pressing Backspace or Delete removes the previously selected point." getpts() has the advantage that it drops down a marker where you click whereas ginput() does not.