Apparatus and method for detecting enlarging ratio or reducing ratio of image data

摘要

An enlarging ratio or reducing ratio detecting apparatus for detecting an enlarging ratio or reducing ratio of digital image data in which the enlarging ratio or reducing ratio of an image is unknown. The apparatus has sectioning means for sectioning the digital image data into horizontal or perpendicular block sizes; conversion means for frequency-converting sectioned blocks into a two-dimension representation; addition means for adding frequencies of the blocks and obtaining a sum of the frequencies; retrieval means for retrieving frequencies at which energy is collecting using an added result; calculation means for calculating an enlarging ratio or reducing ratio based on a retrieved result; and restoration means for restoring an image from image data having the calculated enlarging ratio or reducing ratio.