An image processor for performing resolution conversion on an input image (Dp) having input horizontal and input vertical resolutions to produce a display resolution-converted image (Ddrps) having desired horizontal and desired vertical resolutions, the desired horizontal and desired vertical resolutions being respectively equal to or less than native horizontal and native vertical resolutions of a display device on which the display resolution-converted image (Ddrps) is to be displayed, wherein the image processor includes: a first resolution converter for performing resolution conversion on the input image (Dp) to produce a fixed resolution-converted image (Dprps) having fixed horizontal and fixed vertical resolutions; wherein said fixed horizontal and fixed vertical resolutions are set in advance in the image processor and are equal to said native horizontal and native vertical resolutions respectively; a second resolution converter for performing resolution conversion on the fixed resolution-converted image (Dprps) to produce the display resolution-converted image (Ddrps) having the desired horizontal and desired vertical resolutions; and a frame memory controller adapted to write the fixed resolution-converted image into a frame memory and subsequently to read out the fixed resolution-converted image from the frame memory and supply it to the second resolution converter; characterized in that the first resolution converter includes: a FIFO buffer having a memory area for p pixels where p is an integer greater than 1, a first horizontal resolution converter for converting the input horizontal resolution of the input image (Dp) to produce a first horizontal resolution-converted image having the fixed horizontal resolution; first line buffers for temporarily storing the first horizontal resolution-converted image sequentially output from the first horizontal resolution converter; and a first vertical resolution converter for converting the vertical resolution of the first horizontal resolution-converted image sequentially output from the first line buffers to produce the fixed resolution-converted image (Dprps) having the fixed horizontal and fixed vertical resolutions, wherein the FIFO buffer is adapted to sequentially receive the input image (Dp) starting from a leading pixel of the input image (Dp), and to output the input image (Dp) in m pixel units to the first horizontal resolution converter, where m is an integer greater than 1 and is equal to or less than p, wherein the number of pixels constituting each of the first line buffers is equal to the fixed horizontal resolution, wherein the first horizontal resolution converter is adapted to carry out a filter process on the input image (Dp) output in the m pixel units from the FIFO buffer, wherein the first vertical resolution converter is adapted to carry out a filter process on the first horizontal resolution-converted image sequentially output from the first line buffers to produce the fixed resolution-converted image (Dprps), and wherein the number of pixels p is less than the number of pixels in each horizontal line of the input image (Dp). a first resolution converter for performing resolution conversion on the input image (Dp) to produce a fixed resolution-converted image (Dprps) having fixed horizontal and fixed vertical resolutions; wherein said fixed horizontal and fixed vertical resolutions are set in advance in the image processor and are equal to said native horizontal and native vertical resolutions respectively; a second resolution converter for performing resolution conversion on the fixed resolution-converted image (Dprps) to produce the display resolution-converted image (Ddrps) having the desired horizontal and desired vertical resolutions; and a frame memory controller adapted to write the fixed resolution-converted image into a frame memory and subsequently to read out the fixed resolution-converted image from the frame memory and supply it to the second resolution converter; a FIFO buffer having a memory area for p pixels where p is an integer greater than 1, a first horizontal resolution converter for converting the input horizontal resolution of the input image (Dp) to produce a first horizontal resolution-converted image having the fixed horizontal resolution; first line buffers for temporarily storing the first horizontal resolution-converted image sequentially output from the first horizontal resolution converter; and a first vertical resolution converter for converting the vertical resolution of the first horizontal resolution-converted image sequentially output from the first line buffers to produce the fixed resolution-converted image (Dprps) having the fixed horizontal and fixed vertical resolutions,