Abstract: The present invention relates to an holographic storage medium, where data are stored as data pages having a plurality of pixels within a pixel array. According to the present invention the data pages in the storage medium feature at least two different data types, whereas a first type of data is stored in an inner part of the data pages and at least a second type of data is stored in an outer part of the data pages, the second type of data being stored with a pixel size equal to or less than the pixel size of the first type of data.

Abstract: An optical disc comprising two elementary discs glued to each other by a transparent glue layer. The first elementary disc comprises an information surface according to DVD standard and the second elementary disc comprises an information surface according to CD standard. The present optical disc may be read by a CD player for CD information and by a DVD player for DVD information. The problem of costs and other difficulties for ascending compatibility of DVD players is therefore solved while assuring a simple and smooth transition from CD discs to DVD discs for consumers.