To provide an "image data processor and an image data processing method" for solving the problem that arranging memory cells for redundancy in a memory component results in the increase in the scale of the memory component, and for preventing the abnormality of a pixel value due to the defective memory cell from being hardly conspicuous to such an extent that a user cannot be in visual contact with the abnormality of the pixel value due to the defective memory cell.

When one of a plurality of memory cells assigned to the write-in of the pixel value of a certain pixel is a defective memory cell, the value of the least significant bit among a plurality of bits showing the pixel value is assigned to the defective memory cell, and the pixel value is written in the plurality of memory cells, and the value stored in the defective memory cell is read out as the value of the least significant bit of the pixel value. Thus, even when any defective memory cell exists in the memory component, the value of the least significant bit of the pixel value is always stored in the defective memory cell.