An image processing apparatus for executing processing of input image data, comprising: an input means for inputting raster image data and an output means for outputting raster image data; raster/block vector conversion means for converting raster image data into block vector image data corresponding to blocks each having a predetermined size by segmenting the raster image data into the blocks with the predetermined size and executing vectorization processing for each of the segmented blocks; storage means for storing block vector image data; rasterization means for rasterizing block vector image data into raster image data; and image data transfer control means (2, 3, 4) for controlling transfer of image data as a processing target in the apparatus by causing said raster/block vector conversion means to execute conversion from raster image data into block vector image data when the image data input to the apparatus is raster image data, by causing said storage means to store the block vector image data converted by using said raster/block vector conversion means, by causing execution of said rasterization means for the block vector image data stored in said storage means when it is determined that the format of the image data to be output from said apparatus is the raster image data format, and by causing the output means to output the obtained raster image data, characterized by further comprising: an interface unit for inputting and outputting page vector image data to or from the apparatus; block/page vector conversion means for converting block vector image data corresponding to one page into page vector image data representing the whole page, wherein said block/page vector conversion means is further adapted to convert page vector image data into block vector image data corresponding to blocks each having a predetermined size, wherein said image data transfer control means (2, 3, 4) is further adapted to control transfer of the image data as the processing target in the apparatus by causing said block/page vector conversion means to execute conversion from page vector image data into block vector image data when the image data input to the apparatus is page vector image data, by causing said storage means to store the block vector image data converted by using said block/page vector conversion means, by causing execution of said block/page vector conversion means for converting the block vector image data stored in said storage means when it is determined that the format of the image data to be output from said apparatus is the vector image data format and by causing the interface unit to output the obtained page vector image data, wherein for converting the page vector image data containing an image object into the block vector image data, said block/page vector conversion means comprises: comparison means for comparing a resolution of the image object with a predetermined resolution; first segmentation means for segmenting the image object extending over a plurality of blocks at each block boundary of the plurality of blocks when the resolution of the image object is not more than the predetermined resolution; and second segmentation means for segmenting the image object extending over a plurality of blocks so that a part of the image object beyond each block boundary of the plurality of blocks partially overlaps when the resolution of the image object is higher than the predetermined resolution. an input means for inputting raster image data and an output means for outputting raster image data; raster/block vector conversion means for converting raster image data into block vector image data corresponding to blocks each having a predetermined size by segmenting the raster image data into the blocks with the predetermined size and executing vectorization processing for each of the segmented blocks; storage means for storing block vector image data; rasterization means for rasterizing block vector image data into raster image data; and image data transfer control means (2, 3, 4) for controlling transfer of image data as a processing target in the apparatus an interface unit for inputting and outputting page vector image data to or from the apparatus; block/page vector conversion means for converting block vector image data corresponding to one page into page vector image data representing the whole page, comparison means for comparing a resolution of the image object with a predetermined resolution; first segmentation means for segmenting the image object extending over a plurality of blocks at each block boundary of the plurality of blocks when the resolution of the image object is not more than the predetermined resolution; and second segmentation means for segmenting the image object extending over a plurality of blocks so that a part of the image object beyond each block boundary of the plurality of blocks partially overlaps when the resolution of the image object is higher than the predetermined resolution.