The term anamorphosis (from ancient Greek: transformation) is used in art for the distortion of images or drawings in a regular and specified manner. The actual designs can be seen in their correct proportions with the aid of a spherical mirror. It was initiated by Leonardo Da Vinci and Albracht Dürer in the 16th century in a simple form by change of perspective (e.g. viewing from the side) with the help of special mirrors. The more complicated techniques had their heydays in the 17th and 18th century. It takes a great deal of artistic skill to make a correct anamorphic representation of an object or figure.