To provide an image processor and an image processing method capable of performing compensation to improve the quality of an image, even if there is a frequency component which may have been lost from an image signal.

The image processor includes a domain block extraction unit 2, a domain block orthogonal transformation unit 4, a deterioration factor determination unit 5, a factor composition unit 18, and an inverse transformation unit 19. The domain block extraction unit 2 acquires a domain block S2. The domain block orthogonal transformation unit 4 applies a predetermined transformation operation to the acquired domain block S2, and obtains a domain block DCT factor constellation S4. The deterioration factor determination unit 5 selects a factor corresponding to an image-deteriorated component from the domain block DCT factor constellation S4. According to the selected result by the deterioration factor determination unit 5 and the domain block DCT factor constellation S4, the factor composition unit 18 generates a synthetic DCT factor constellation S18. The inverse transformation unit 19 applies a predetermined inverse transformation operation to the synthetic DCT factor constellation S18, and outputs an expanded partial image S19.