1. A data processing method comprising:
an encoding step of encoding image data into a plurality of bit streams arranged in ascending order of resolution levels;
a first key generation step of generating a plurality of keys for respective resolution levels of the encoded image data, the first key generation step generating a key for the highest resolution level by converting a basic key with a predetermined function and generating respective keys for other resolution levels by repetitively converting a key for a preceding resolution level with the predetermined function;
an encryption step of encrypting each of the bit streams using a corresponding one of the plurality of keys;
a delivery step of delivering all of the encrypted bit streams in ascending order of resolution levels to a user with a key for a predetermined resolution level corresponding to the user;
a second key generation step of generating respective keys for resolution levels under the predetermined resolution level by repetitively converting the key for the predetermined resolution level with the predetermined function; and
a decryption step of sequentially applying the keys generated in the second key generation step in order of generation to the delivered bit streams in order of delivery, thereby decrypting the encrypted bit stream in the predetermined resolution level using the key for the predetermined resolution level and decrypting the encrypted bit stream in each of resolution levels under the predetermined resolution level using the respective keys.
2. A data processing method according to claim 1, wherein the predetermined function is a one-way function.
3. A data processing method according to claim 1, wherein an encryption method of the encrypted key is a private key encryption algorithm.
4. A data processing method according to claim 1, wherein an encryption method of the encrypted key is a public key encryption algorithm.
5. A data processing method according to claim 1, wherein the data having a hierarchical structure is image data.
6. A data processing method according to claim 1, wherein the data having a hierarchical structure is multimedia data.
7. A data processing method according to claim 1, wherein a key used for encrypting or decoding image data in a highest level of the hierarchy is specific private information or information dependent on the data.
8. A data processing method according to claim 1, wherein the hierarchical structure is a hierarchical structure based on resolution, and the resolution becomes higher as a level of the hierarchy is higher.
9. A data processing method according to claim 1, wherein the hierarchical structure is a hierarchical structure based on resolution, and a degree of importance becomes higher as a level of the hierarchy is higher.
10. A data processing method according to claim 1, wherein the hierarchical structure is a hierarchical structure based on SNR, and the SNR becomes lower as a level of the hierarchy is higher.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An apparatus to measure the speed of a moving imaging surface having a primary movement direction, the apparatus comprising:
marking means for providing a plurality of reference patterns formed of slant lines provided on the moving surface, wherein the marking means includes means for creating and developing an electrostatic image on the imaging surface;
a sensor to detect the plurality of reference patterns being moved on the moving surface, wherein the sensor produces a timestamp when it detects a reference pattern;
an encoder comprising at least one encoder roll associated with the moving imaging surface, the encoder generating encoder pulses;
an ROS master clock to generate discrete clock pulses; and
a logic circuit coupled to the sensor, the encoder, and the master clock to determine the speed of the moving surface by:
counting the number of encoder pulses generated by the encoder between a first timestamp and a second timestamp;
determining a leading fractional encoder count relative to the first timestamp;
determining a trailing fractional encoder count relative to the second timestamp; and
determining an elapsed interval of time between the first timestamp and the second timestamp;
wherein the reference patterns being spaced along the moving imaging surface by a predetermined distance substantially corresponding to a circumference of the encoder roll.
2. The apparatus according to claim 1, wherein the logic circuit is at least one of field programmable gate array (FPGA), application specific integrated circuit (ASIC), or complex programmable logic device (CPLD).
3. The apparatus according to claim 2, wherein the plurality of reference patterns are arranged in a chevron pattern of regularly spaced stripes.
4. The apparatus according to claim 3, wherein determining a leading fractional encoder is counting the discrete clock pulses that occur between the first time stamp and a next encoder pulse.
5. The apparatus according to claim 3, wherein determining a trailing fractional encoder count is counting the discrete clock pulses that occur between the second time stamp and a next encoder pulse.
6. The apparatus according to claim 3, the apparatus further comprising:
a controller to control a printing system based on the determined speed of the moving surface.
7. The apparatus according to claim 6, wherein the moving surface includes a plurality of image panel zones each image panel corresponding to a page image desired to be printed, with successive panel zones separated by inter panel zones, wherein the controller provides a control parameter indicating whether an image to be generated on an upcoming panel zone is to be fixed to a first side or a second side of a print sheet.
8. A method to determine the speed of a moving surface having a primary movement direction, the method comprising:
receiving from a sensor a plurality of timestamps indicative of a plurality of reference patterns being moved on the moving surface;
receiving encoder pulses from an encoder associated with the moving surface;
receiving discrete clock pulses from an ROS master clock; and
processing with a logic unit the received timestamps, encoder pulses, and discrete clock pulses to determine the speed of the moving surface by:
counting the encoder pulses generated between a first timestamp and a second timestamp;
determining a leading fractional encoder count relative to the first time stamp;
determining a trailing fractional encoder count relative to the second time stamp;
determining an elapsed interval of time between the first timestamp and the second timestamp.
9. The method according to claim 8, wherein the logic unit is at least one of field programmable gate array (FPGA), application specific integrated circuit (ASIC), or complex programmable logic device (CPLD).
10. The method according to claim 9, wherein the plurality of reference patterns are arranged in a chevron pattern of regularly spaced stripes.
11. The method according to claim 10, wherein determining a leading fractional encoder is counting the discrete clock pulses that occur between the first time stamp and a next encoder pulse.
12. The method according to claim 10, wherein determining a trailing fractional encoder count is counting the discrete clock pulses that occur between the second time stamp and a next encoder pulse.
13. The method according to claim 10, the method further comprising:
controlling a printing system based on the determined speed of the moving surface.
14. The method according to claim 13 wherein the moving surface includes a plurality of image panel zones each image panel corresponding to a page image desired to be printed, with successive panel zones separated by inter panel zones, wherein the controller provides a control parameter indicating whether an image to be generated on an upcoming panel zone is to be fixed to a first side or a second side of a print sheet.
15. A document processing system, comprising:
a photoreceptor that continuously moves along a closed path;
at least one raster output scanner (ROS) located along the closed path of the photoreceptor, the ROS operable to generate a latent image on a portion of the photoreceptor based on a clock input;
a clock providing a clock output signal to the ROS;
a sensor to detect a plurality of reference patterns being moved on the photoreceptor, wherein the sensor produces a timestamp when it detects a reference pattern;
an encoder coupled to the photoreceptor, wherein movement of the photoreceptor causes the encoder to generate encoder pulses;
a controller coupled with the ROS to selectively operate the document processing system according to a photoreceptor speed; and
logic circuit to determine photoreceptor speed from the encoder pulses, the timestamp, and the clock output signal by:
counting the number of encoder pulses generated by the encoder between a first timestamp and a second timestamp;
determining a leading fractional encoder count relative to the first time stamp;
determining a trailing fractional encoder count relative to the second time stamp; and
determining an elapsed interval of time between the first timestamp and the second timestamp.
16. The document processing system according to claim 15, wherein the logic circuit is at least one of field programmable gate array (FPGA), application specific integrated circuit (ASIC), or complex programmable logic device (CPLD).
17. The document processing system according to claim 16, wherein the plurality of reference patterns are arranged in a chevron pattern of regularly spaced stripes.
18. The document processing system according to claim 17, wherein determining a leading fractional encoder is counting discrete clock pulses from the clock output signal that occur between the first time stamp and a next encoder pulse.
19. The document processing system according to claim 17, wherein determining a trailing fractional encoder count is counting the discrete clock pulses from the clock output signal that occur between the second time stamp and a next encoder pulse.
20. The document processing system according to claim 19, wherein the moving surface includes a plurality of image panel zones each image panel corresponding to a page image desired to be printed, with successive panel zones separated by inter panel zones, wherein the controller provides a control parameter indicating whether an image to be generated on an upcoming panel zone is to be fixed to a first side or a second side of a print sheet.