A method and apparatus of image processing includes first and second memories and first and second copy protector units. The first memory stores a first reference value representing a first characteristic quantity of a predetermined background dot pattern. The first copy protector unit performs a first copy protection operation for detecting a characteristic quantity from an image, comparing the characteristic quantity with the first reference value, and determining whether the characteristic quantity is identical to the first reference value. The second memory stores a second reference value representing a second characteristic quantity of the predetermined background dot pattern. The second copy protector unit performs a second copy protection operation, different from the first copy protection operation, for detecting a characteristic quantity from the image, comparing the characteristic quantity with the second reference value, and determining whether the characteristic quantity is identical to the second reference value.