-For the RGB ones: all the RGB functions follow the same logic, the only difference
      being the function called for each color. First of all, I extract the colors
      (1-red, 2-green, 3-blue), then I apply each respective function, then I obtain
      the output by concatenating the three results( cat(3, R_rez, V_rez, A_rez));
      
      -For surrounding_points: Initially, the points are the biggest integer values
      bigger then (x, y) -> (x1, y1) and the incremented value of each (x2, y2).
      If the point is at the border, the values are decremented.
      
      -For nearest-neighbour:
      
      *nn_2x2 - I choose the values of the pixel by its quadrant
  -Pentru nearest-neighbour:
  
      -For bilinear:
      
      *bilinear_rotate - I determine if a point is outside the image by comparing it
      with the borders(x with [1, n], y with [1, m])
  
      For bicubic:
      
      *bicubic_coef - to make the code more readable, the matrix containing the values of
      the function and its derivatives is the result of concatanating 4 other matrixes
      (AUXfin = cat(2, cat(2, AUXf, AUXfy)', cat(2, AUXfx, AUXfxy)')')