An image processing apparatus and method including an encoder circuitry for generating encoded data blocks from input data blocks of an image, and write circuitry for storing the encoded data blocks to memory for subsequent access by decoding circuitry. For each input data block, identifier generation circuitry generates an identifier value that is dependent on the input data block. A lookup storage stores predetermined information relating to at least one encoded data block and stored within the lookup storage in association with the identifier value for the corresponding input data block. For a current input data block, a check is performed to determine whether a match exists between the identifier value generated for the current input data block and an identifier value stored in the lookup storage. In a match, the predetermined information is used by the write circuitry when performing the required write operation.