A data processing device includes an input unit which acquires image data, a meaning information extraction unit which extracts meaning information indicating a feature of an object image included in an image represented by the image data, a compression specifying unit which determines an initial value of a compression ratio, a compression unit which compresses the image data according to the compression ratio to generate compressed image data, and a determination unit which determines whether or not the meaning information can be extracted from the compressed image data. The compression specifying unit further changes the compression ratio from the initial value according to a result of the determination by the determination unit, and when the compression ratio is changed, the compression unit further compresses the image data according to the changed compression ratio to newly generate compressed image data.