Irfan Khan has signed Pooja Bhatt's next home production 'Rog' as a lead male artiste. Ayush Rana will direct this film. 'I play a detective in Pooja's film. It is an interesting script", he says. After doing lots of negative roles he is going to be positive in upcoming films like - 'Rog', 'Dubai Returned' and 'Sapna Hai'. He reveals, "Frankly, acting is not about how positive or negative a character is. It's about justifying your role. I am not concentrating on portraying grey characters but interesting ones. It isn't the negativity that has drawn me to the characters I've portrayed so far, but their depth."