matlab

% Differentiation can be used to see where the colour changes from black to white or vice versa.

% Example code for collecting the data and getting rid of noise

clc;
clear all;
close all;
MyRawImage = double(imread('letter_A_noisy.jpg'));
OneLineData = MyRawImage(850,1:end)
plot(OneLineData);
ws = 6;
% OneLineDataAve(1) = (OneLineDataAve(1)+OneLineDataAve(2)+OneLineDataAve(3)+OneLineDataAve(4))/4;
% OneLineDataAve(2) = (OneLineDataAve(2)+OneLineDataAve(3)+OneLineDataAve(4)+OneLineDataAve(5))/4;
for i=1:length(OneLineData)-(ws-1)
    % OneLineDataAve(i) = (OneLineData(i)+OneLineData(i+1)+OneLineData(i+2))/3;
    OneLineDataAve(i) = sum(OneLineData(i:i+(ws-1)))/ws;
end;
hold OneLineDataplot(OneLineDataAve)

% DataAveDif(1) = OneLineDataAve(2) - OneLineDataAve(1);
% DataAveDif(2) = OneLineDataAve(3) - OneLineDataAve(2);

%% This for loop is made obsolete by the line of code beneath it %%
% for i=1:length(OneLineDataAve)-1
%   DataAveDif(i) = OneLineDataAve(i+1) - OneLineDataAve(i);
% end;
DataAveDif = abs(OneLineDataAve(2:length(OneLineDataAve)) - OneLineDataAve(1:length(OneLineDataAve)-1)) % abs() converts to absolute value
% The purpose of the above line is to take the differential of the average to see where the data changes from high to low.
figure;
plot(DataAveDif);
xlim([850 1500]);

[pks,locs] = findpeaks(DataAveDif,'MinPeakHeight',25,'MinPeakDistance',6); % findpeak is a MATLAB function, which means it has options
% MinPeakHeight lets you only look at peaks above a certain height
% MinPeakDistance allows you to only take the highest peak in a specified domain
figure;
plot(DataAveDif);
hold on;
plot(locs,pks,'or'); % Plots a red o at every peak
xlim([850 1500]);

widths = locs(2:end) - locs(1:end-1)
% The locs variable are the peaks, using that you can calculate the widths using the above line of code
% If you locate the minimum width, and divide everything by it, you will have numbers along the line of 1.0, 1.3, 3.0, 3.5, etc...
% Then you must round the values to get the barcode ratio lengths (3, 1, 1, 3, etc...);
widths = round(widths/min(widths))