demo3

Contents

initialize

clear
rgb = im2double(imread('birds1.jpg'));
imshow(rgb);
do_input = false;
if ~do_input
    load demo3
end

select pixel values

if do_input
	[c r p] = impixel;
	save demo3 c r p
end
disp(p)

    1.0000    0.2275    0.0039
    0.1922    0.5294    0.0078
    0.0235    0.2235    0.8275

show pixel locations

imshow(rgb);
hold on
plot(c,r,'wo');
for n=1:length(c)
    text(c(n)+10,r(n),sprintf('%d',n),'Color','w');
end
hold off

instantiate distance tool

imshow(rgb);
if do_input
    hd = imdistline;
else
     hd = imdistline(gca, pts(:,1), pts(:,2));
end
% sometimes the distance tool is not rendered properly when publishing

distance api

The Distance tool contains a structure of function handles, called an API, that can be used to retrieve distance information and control other aspects of Distance tool behavior.

api = iptgetapi(hd);
w = api.getDistance();
fprintf('distance %g pixels\n',w);
pts = api.getPosition();
if do_input
     save demo3 c r p pts
end
point1 = pts(1,:);
point2 = pts(2,:);
fprintf('point1 %g  %g  point2 %g  %g\n',point1,point2);
fprintf('norm(point1-point2) = %g\n',norm(point1-point2));

% delete(api)
% clear api hd

distance 129 pixels
point1 135.5  189.5  point2 135.5  318.5
norm(point1-point2) = 129

Published with MATLAB® R2014a