Matlab - Como medir distancia entre 2 puntos en una imagen?

%Example 1

%Insert a Distance tool into an image. Use makeConstrainToRectFcn to specify a drag constraint

 %function that prevents the Distance tool from being dragged outside the extent of the image.

 %Right-click the Distance tool and explore the context menu options.

figure, imshow('pout.tif');

h = imdistline(gca);

api = iptgetapi(h);

fcn = makeConstrainToRectFcn('imline',...

                              get(gca,'XLim'),get(gca,'YLim'));

api.setDragConstraintFcn(fcn);

%Example 2

%Position endpoints of the Distance tool at the specified locations.

close all, imshow('pout.tif');

h = imdistline(gca,[10 100],[10 100]);

%Delete the Distance tool.

%api = iptgetapi(h);

%api.delete();

%Example 3

%Use the Distance tool with XData and YData of associated image in non-pixel units. This example %%requires the boston.tif image from the Mapping Toolbox software, which includes material 

%copyrighted by GeoEye™, all rights reserved.

start_row = 1478;

end_row = 2246;

meters_per_pixel = 1;

rows = [start_row meters_per_pixel end_row];

start_col = 349;

end_col = 1117;

cols = [start_col meters_per_pixel end_col];

img  = imread('boston.tif','PixelRegion',{rows,cols});

figure;

hImg = imshow(img);

title('1 meter per pixel');

% Specify initial position of distance tool on Harvard Bridge.

hline = imdistline(gca,[271 471],[108 650]);

api = iptgetapi(hline);

api.setLabelTextFormatter('%02.0f meters');

% Repeat process but work with a 2 meter per pixel sampled image. Verify

% that the same distance is obtained.

meters_per_pixel = 2;

rows = [start_row meters_per_pixel end_row];

cols = [start_col meters_per_pixel end_col];

img  = imread('boston.tif','PixelRegion',{rows,cols});

figure;

hImg = imshow(img);

title('2 meters per pixel');

% Convert XData and YData to meters using conversion factor.

XDataInMeters = get(hImg,'XData')*meters_per_pixel;

YDataInMeters = get(hImg,'YData')*meters_per_pixel;

% Set XData and YData of image to reflect desired units.    

set(hImg,'XData',XDataInMeters,'YData',YDataInMeters);

set(gca,'XLim',XDataInMeters,'YLim',YDataInMeters);

% Specify initial position of distance tool on Harvard Bridge.

hline = imdistline(gca,[271 471],[108 650]);

api = iptgetapi(hline);

api.setLabelTextFormatter('%02.0f meters');