Method and apparatus for position identification in runlength compression data

摘要

A position in runlength compression data corresponding to a desired position in original data can be found fast. Index correspondence information is generated for representing correspondence between indexes representing predetermined positions in data arrangement of the original data having a plurality of values and positions corresponding thereto in the runlength compression data. The index closest to the desired position in the original data and an offset of the desired position from the index are found. Based on the index correspondence information, the corresponding index in the runlength compression data is found. The position corresponding to the desired position is then found in the runlength compression data, based on the corresponding index and the offset.