dos commands through the recording unit 6 the compression is conducted by a variable length encoding or a fixed length encoding for example by dct conversion of the image as will be explained later followed by entropy encoding also there is provided a function of counting the amount of compressed codes without the supply thereof to the recording unit 6 for this purpose there is provided a counting circuit 16 for counting the amount of compressed encoded data prior to the supply thereof to the recording unit 6 the recording unit 6 is provided with a recording medium such as a semiconductor memory or a tape shaped medium is capable of information exchange with the control unit of recording or reading of arbitrary digital data at an arbitrary physical address of the recording medium and of counting the empty capacity of said recording medium the control unit 7 controls the entire apparatus by controlling the units 2 u2013 6 and is also capable of controlling the image data files in the recording medium through the recording unit more specifically the control unit 7 correlates the file information with the physical addresses on the recording medium as in a disk operating system employed in a computer system and is therefore capable of controlling the mode of recording of files compressed image data on the recording medium and also the empty capacity thereof if the compressed codes have to be stored in divided plural parts with a limited recording unit each the control unit 7 causes the recording unit.