To provide a picture data processor capable of reducing a cost.

In a data converter 1, a data memory part 2 composed of a DRAM is integrated and formed. In the data memory part 2, multilevel data for two lines are stored by a filter part 45, error data are stored by a halftone part 47 and reduction data are stored by a resolution conversion part 48 respectively tentatively. The data are respectively read out and written every time the multilevel data for one row are processed with an interval shorter than the refresh interval of the DRAM for constituting the data memory part 2 by the filter part 45, the halftone part 47 and the resolution conversion part 48.