%
% This script reads an image, lets you pick some points and then saves
% picked data into a file.
%
% BEWARE: I've uploaded this script just to keep it at hand. It's not
% bug-free and you should not trust it.
%
% The script works nice with GNU Octave v3.6.2
% 
% Cheers,
%   Stefano

close all
clear
clc

page_screen_output(0);


% ###############################################################
% ###################  Scaling functions  #######################
% ###############################################################

% ------ Linear scaling 
function xNew = lin_scale(xIn, xOrig, xXaxis, xOrig_value, xXaxis_value)

  xScaleFactor = (xXaxis_value - xOrig_value) / (xXaxis - xOrig);

  % Translating the points
  xInTransl = xIn - xOrig;
  
  % Scaling
  xInScaled = xInTransl*xScaleFactor;
  
  % And then translating again
  xNew = xInScaled + xOrig_value;
 
endfunction

% ------ Log scaling
function xNew = log_scale(xIn, xOrig, xXaxis, xOrig_value, xXaxis_value)
 
  % Computing logaritms of input values
  log_xOrig_value  = log(xOrig_value);
  log_xXaxis_value = log(xXaxis_value);

  xScaleFactor = (log_xXaxis_value - log_xOrig_value) / (xXaxis - xOrig);

  % Translating the points
  xInTransl = xIn - xOrig;
  
  % Linearly scaling log data
  xInScaled = xInTransl*xScaleFactor;
  
  % Then translating again
  xInTranslScaled = xInScaled + log_xOrig_value;

  % And finally converting log-data to actual data
  xNew = exp(xInTranslScaled);

endfunction



% ###########################################################
% ######################   M A I N   ########################
% ###########################################################

% Read image
imname = input('Name of the image to be read: ', 's');
im = imread(imname);

image(im)
axis equal

% Select axis
fprintf('You now have to select three points:\n');
fprintf(' 1) The plot origin (bottom left axis point)\n');
fprintf(' 2) One point on the X axis\n');
fprintf(' 3) One point on the Y axis\n');
fprintf('Also, you will be asked for the corresponding value.\n\n');

fprintf('Pick the origin\n')
[xOrig, yOrig] = ginput(1);
xOrig_value = input(' X value for the origin: ');
yOrig_value = input(' Y value for the origin: ');

fprintf('Pick one point on the X axis\n');
[xXaxis, dummy] = ginput(1);
xXaxis_value = input('X value for the picked point: ');

fprintf('Now Pick one point on Y axis\n');
[dummy, yYaxis] = ginput(1);
yYaxis_value = input('Y value for the picked point: ');

% Now get points until RETURN is pressed
fprintf('Now pick as many points as you like. Press <RETURN> on the image');
fprintf(' when you are done.\n')

[xPicked, yPicked] = ginput();

% ------  Elaborating picked points  ------


% Is some scaling Logarithmic?
% no -> linear linear plot
fprintf('\nIs the plot logarithmic?\n');
fprintf('no -> linear linear plot\n');
fprintf('x  -> semilogx\n');
fprintf('y  -> semilogy\n');
fprintf('xy -> loglog\n');

isLog = input('','s');

switch(isLog)
  case 'no'
    xPickedFinal = lin_scale(xPicked, xOrig, xXaxis, xOrig_value, xXaxis_value);
    yPickedFinal = lin_scale(yPicked, yOrig, yYaxis, yOrig_value, yYaxis_value);
    fprintf('You have choosed a linear-linear plot. \n');
  case 'x'
    xPickedFinal = log_scale(xPicked, xOrig, xXaxis, xOrig_value, xXaxis_value);
    yPickedFinal = lin_scale(yPicked, yOrig, yYaxis, yOrig_value, yYaxis_value);
    fprintf('You have choosed a semilogx-type plot. \n');
  case 'y'
    xPickedFinal = lin_scale(xPicked, xOrig, xXaxis, xOrig_value, xXaxis_value);
    yPickedFinal = log_scale(yPicked, yOrig, yYaxis, yOrig_value, yYaxis_value);
    fprintf('You have choosed a semilogy-type plot. \n');
  case 'xy'
    xPickedFinal = log_scale(xPicked, xOrig, xXaxis, xOrig_value, xXaxis_value);
    yPickedFinal = log_scale(yPicked, yOrig, yYaxis, yOrig_value, yYaxis_value);
    fprintf('You have choosed a loglog-type plot. \n');
endswitch

% Save results? Are you happy with them?
fprintf('Save results?\n');
saveMe = input('  Yes: write filename || No: hit <RETURN> ', 's');

if ( numel(saveMe) > 1 )

  fID = fopen(saveMe,'w');
  fprintf(fID, '%% Free Software is needed for Free Science\n');
  fprintf(fID, '%% x | data\n');

  for ii = 1:numel(xPicked)
    fprintf(fID, '%e %e\n', xPickedFinal(ii), yPickedFinal(ii));
  end

  fclose(fID);
end