% With this program you can:
% load an single image or a frame from a video, measure (semi-manually) the
% distance between two points (in pixels), and determine the scale (pix to
% mm conversion).
% by R. Zenit, Brown University
% last updated September 8, 2020


%clear all
%close all

% video file
%path='';
%filename= 'scale.MOV'
% image file
filename=['outsforscale.png'];
%filename=['profforscale.bmp'];

% type the physical distance in INCHES
Length= .3; %NOZZLE LENGTH

%For image file
photo=imread(filename);

%For video
%Frame to be uploaded, if video is used
% Firstframe=400;
% mov3 = VideoReader(filename);
% numberOfFrames = mov3.NumberOfFrames;
% vidHeight = mov3.Height;
% vidWidth = mov3.Width;
% photo= read(mov3,Firstframe);



figure(1)
clf
imshow(photo,'InitialMagnification', 200);
axis image;

hold on
title('Click on first point')
pos1=ginput(1)
x1=pos1(1);
y1=pos1(2);
plot(x1,y1,'m +')

title('Click on second point')
pos2=ginput(1)
x2=pos2(1);
y2=pos2(2);
plot(x2,y2,'m +')

k=line([x2 x1],[y2,y1]);
set(k,'linestyle','--','color','r')

distance_pix=sqrt((x1-x2)^2+(y1-y2)^2);

% Calculate conversion factor
% in pix/mm
scale=distance_pix/Length
title(['Conversion factor ', num2str(scale), ' pix/mm'])