EVERY image is perceivable   vs     NO image is perceivable

C                                                 N

    O                                         O    

        N                                 I        

            T                         T            

                R                 C                

                    A         I                    

                         D                         

                    A         I                    

                R                 C                

            T                         T            

        N                                 I        

    O                                         O    

C                                                 N

SOME image is perceivable      &  SOME image is NOT perceivable