code: def delta_e_cie1994(lab_color_vector, lab_color_matrix,
                      K_L=1, K_C=1, K_H=1, K_1=0.045, K_2=0.015):
      
      C_1 = numpy.sqrt(numpy.sum(numpy.power(lab_color_vector[1:], 2)))
      C_2 = numpy.sqrt(numpy.sum(numpy.power(lab_color_matrix[:, 1:], 2), axis=1))
  
      delta_lab = lab_color_vector - lab_color_matrix
  
      delta_L = delta_lab[:, 0].copy()
      delta_C = C_1 - C_2
      delta_lab[:, 0] = delta_C
  
      delta_H_sq = numpy.sum(numpy.power(delta_lab, 2) * numpy.array([-1, 1, 1]), axis=1)
      # noinspection PyArgumentList
      delta_H = numpy.sqrt(delta_H_sq.clip(min=0))
  
      S_L = 1
      S_C = 1 + K_1 * C_1
      S_H = 1 + K_2 * C_1
  
      LCH = numpy.vstack([delta_L, delta_C, delta_H])
      params = numpy.array([[K_L * S_L], [K_C * S_C], [K_H * S_H]])
  
      return numpy.sqrt(numpy.sum(numpy.power(LCH / params, 2), axis=0))
docs: Calculates the Delta E (CIE1994) of two colors.
  
      K_l:
        0.045 graphic arts
        0.048 textiles
      K_2:
        0.015 graphic arts
        0.014 textiles
      K_L:
        1 default
        2 textiles