To provide an image compression apparatus which simply reduces mosquito noise generated with compression processing as much as possible.

The image compression apparatus includes an image compression means 10 which generates image compression data by quantizing original image data based on a predetermined quantizing table, while converting the original image data from a space coordinate to a frequency coordinate. It is provided with an image expansion means 11 which generates expanded image data by inversely quantizing the image compression data, and simultaneously converting the frequency coordinate to the space coordinate; a binarization means 12 which carries out binarization of the above original image data and the expanded image data; and a compression rate evaluation means 13 which evaluates properness of a compression rate of the original image data by the image compression means 10 based on a variance value of respective binarization image data which are binarized by the binarization means 12.

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