#### Brightness

C
```function y = brightness(red, green, blue)
% brightness: returns 1 if the color is light otherwise 0
% INPUT: RGB-value of the color (red, green, blue)
% OUTPUT: 0 or 1 (0 dark, 1 light)
% The function used the nearest neighbor algorithm

% train set for various rgb-values and its brightness
% the set contains vectors with dimension 4x1
% [r, g, b, brightness]
train_set = [2, 99, 255, 1;
37,44,58,0;
139, 169, 229,1;
14, 255, 10, 1;
2, 28, 1, 0;
20, 33, 20, 0;
252, 227, 65,1;
71, 65, 24, 0;
168, 80, 80,1;
119, 35, 90, 0;
186, 13, 126, 1;];

function length = eulidean(v1, v2)
% eulidean: calculates the eulidean length between two vectors (3x1)
% The calculation contains only the RGB-values! (3x1)
% HELPER-FUNCTION
length = sqrt((v2(1)-v1(1))^2 + (v2(2)-v1(2))^2 + (v2(3)-v1(3))^2);
endfunction

rgb = [red green blue];
x1 = train_set(1,:);
x2 = x1(1:3);
min = eulidean(rgb,x2);
index = 1;

for i = 2:length(train_set)
x1 = train_set(i,:);
x2 = x1(1:3);
result = eulidean(rgb,x2);
if (result < min)
min = result;
index = i;
end
end

y = train_set(index,:)(4);

endfunction```  