Implementations relate to detecting spherical images. In some implementations, a computer-executed method includes obtaining an image, examining at least one characteristic of the image, and determining that the image is a spherical image based on the at least one examined characteristic. The method modifies metadata associated with the image to designate the image for spherical display.

A manufacture for encoding information from which a position of an optical pen tip can be derived, said manufacture includes a display medium having a supporting base and upon which is encoded a two dimensional code pattern that is continuously arranged on an entire surface of the supporting base; wherein the pattern is formed by a sequence of narrow parallel bands, including at least two parallel lines, of which one line is a base line the remaining lines are secondary lines; wherein each narrow parallel band includes a sequence of dots, the dots being arranged in a pre-determined position in order to represent a number at a selected number base.