An image processing device for processing image data to be output through a screen, the device comprising: a memory configured to store image data of at least one frame; a read address calculator configured to calculate a read address of output image data that is transformed from the input image data, the read address being used to transform the input image data read out from the memory to the output image data through coordinate conversion; a memory interface configured to write the input image data to the memory, and to read out the input image data from the memory as the output image data based on the read address of the output image data calculated by the read address calculator; a memory access controller configured to control reading process of the memory interface so as to keep a number of pixels in a main scanning direction of the output image data read out from the memory smaller than a number of pixels in a main scanning direction of the screen, wherein the number of pixels in the main scanning direction of the output image data read out from the memory is calculated such that a signal output corresponding to the frequency characteristics in the main scanning direction of the image data to be output is kept at a constant level such that a degradation on the screen is almost absent; an image expander configured to expand the output image data read out from the memory to generate expanded image data so as to increase the number of pixels in the main scanning direction of the output image data to the number of pixels in the main scanning direction of the screen; and an image output configured to encode the expanded image data in a desired format and to output the encoded image data through the screen. a memory configured to store image data of at least one frame; a read address calculator configured to calculate a read address of output image data that is transformed from the input image data, the read address being used to transform the input image data read out from the memory to the output image data through coordinate conversion; a memory interface configured to write the input image data to the memory, and to read out the input image data from the memory as the output image data based on the read address of the output image data calculated by the read address calculator; a memory access controller configured to control reading process of the memory interface so as to keep a number of pixels in a main scanning direction of the output image data read out from the memory smaller than a number of pixels in a main scanning direction of the screen, wherein the number of pixels in the main scanning direction of the output image data read out from the memory is calculated such that a signal output corresponding to the frequency characteristics in the main scanning direction of the image data to be output is kept at a constant level such that a degradation on the screen is almost absent; an image expander configured to expand the output image data read out from the memory to generate expanded image data so as to increase the number of pixels in the main scanning direction of the output image data to the number of pixels in the main scanning direction of the screen; and an image output configured to encode the expanded image data in a desired format and to output the encoded image data through the screen.