% x = ImageRecognition(img,minsize,threshold,crop,rotate,plotting)
%
% Helper function for ExtractCoordinates. Finds the x-coordinate of the 
% centroid of an object in an image. 
%
% img = Image 
% minsize = Minimum size of the searched area in pixels (e.g. 100)
% threshold = Threshold for black-and-white conversion (0..1)
% crop = Amount video is cropped from bottom. Used to discard substrate
%        from analysis
% rotate = Video rotation angle (deg). Used to straighten skewed videos.
% plotting = Whether the image is showed (1) or not (0).
%
% x = x-coordinate of the centroid of an object
%
% Image must contain only one object in specified size range.

function [x] = ImageRecognition(RGB,minsize,threshold,crop,rotate,plotting)
% This script is not relevant for writing the report, but it might be
% interesting. Probably not.

% If no objects are found, return -1;
x=-1;

% Rotate image if needed
if rotate ~= 0
    temp=imrotate(RGB,rotate);
    % White border instead of black
    rotationmask = ~imrotate(true(size(RGB)),rotate);
    temp(rotationmask&~imclearborder(rotationmask)) = 255;
    RGB=temp;
end

% Convert to black and white
BW = im2bw(rgb2gray(RGB),threshold);

% Invert image
BW=not(BW);

% Crop image if needed
if crop ~= 0
    BW=imcrop(BW,[0 0, size(BW,2), size(BW,1)-crop]);
end

% Fill any holes, so that regionprops can be used to estimate
% the area enclosed by each of the boundaries
BW = imfill(BW,'holes');

% Find boundaries
[B,L] = bwboundaries(BW,'noholes');

% Find centroid and area of objects
stats = regionprops(L,'Area','Centroid');

% Counts how many objects are found. Must not exceed 1.
count=0;

% Show image
if plotting == 1
    imshow(not(BW)); 
end

% Loop over objects
for k = 1:length(B)

  % Find objects of spesified size
  if (stats(k).Area >= minsize)
    count=count+1;
    if count > 1  % Too many droplets, return -2
      x=-2;
      return;
    end;
    x=stats(k).Centroid(1);
  end;
end;

if plotting == 1
    hold on;
    plot([x,x],[0, size(BW,1)],'-r');
    hold off;
end