Apparatus and method for controlling image quality reduction of image information
An apparatus 10 for controlling image quality reduction of image information, which is related to the present invention, has a VLD 30 for introducing a code stream input 21 thereinto of image information based on an MPEG, a reverse circuit 40 for introducing a pre-reverse level 32 thereinto from the VLD 30 , and a VLC 50 for introducing a RUN 31 from the VLD 30 and an after-reverse level 42 from the reverse circuit 40 , and a code stream output 51 of image information based on the MPEG is generated by the VLC 50 and is sent therefrom, and this code stream output 51 is provided for a digital copy.
1. An apparatus for controlling image quality reduction of image information for reducing image quality of image information and conducting a digital copy by means of a digital information compression technology, comprising:
a reverse section for reversing a specific code by means of a code stream of said image information, and outputting it after reducing image quality of said image information by means of reverse of one code or a plurality of codes, wherein said reverse section specifies a reverse position by means of coordinates within each unit block of image information and wherein said reverse section has a random number generator for generating a random number for designating said coordinates.
2. An apparatus for controlling image quality reduction of image information according to claim 1 , wherein said reverse section reverses a code on a coefficient table of discrete cosine transform.
3. An apparatus for controlling image quality reduction of image information according to claim 1 , wherein said reverse section reverses a code within a range in which a code stream can be combined by means of a digital information compression technology without changing data length of said code stream.
4. An apparatus for controlling image quality reduction of image information according to claim 1 , wherein said reverse section changes a deterioration degree of image quality by specifying a reverse position of a code.
5. An apparatus for controlling image quality reduction of image information according to claim 1 , wherein said reverse section conducts image quality reduction of image information by dividing it into two steps or more than or equal to three steps.
6. An apparatus for controlling image quality reduction of image information according to claim 1 , wherein said reverse section conducts image quality reduction for at least one of a Y component, a Cr component and a Cb component of image information.
7. A method of controlling image quality reduction of image information for reducing image quality of image information and conducting a digital copy by means of a digital information compression technology, comprising steps of:
reversing a specific code by means of a code stream of said image information, and outputting it after reducing image quality of said image information by means of reverse of one code or a plurality of codes, wherein said reverse step includes a step of specifying a reverse position by means of coordinates within each unit block of image information, said coordinates being designated by generating at least one random number.
8. A method of controlling image quality reduction of image information according to claim 7 , wherein said reverse step includes a step of reversing a code on a coefficient table of discrete cosine transform.
9. A method of controlling image quality reduction of image, information according to claim 7 , wherein said reverse step includes a step of reversing a code within a range in which a code stream can be combined by means of a digital information s compression technology without changing data length of said code stream.
10. A method of controlling image quality reduction of image information according to claim 7 , wherein said reverse step includes a step of changing a deterioration degree of image quality by specifying a reverse position of a code.
11. A method of controlling image quality reduction of image information according to claim 7 , wherein said reverse step includes a step of conducting image quality reduction of image information by dividing it into two steps or more than or equal to three steps.
12. A method of controlling image quality reduction of image information according to claim 7 , wherein said reverse step includes a step of conducting image quality reduction for at least one of a Y component, a Cr component and a Cb component of image information.