Image processing apparatus and method for extracting predetermined additional information from digital image data representing an original

• US 6,337,930 B1
• Filed: 05/14/1998
• Issued: 01/08/2002
• Est. Priority Date: 06/29/1993
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Owada, Mitsuru, Kimura, Takeo, Nagashima, Yoshitake
• Primary Examiner(s): Nguyen, Madeleine
• Application Number:
  US09/078,496
• Time in Patent Office: 1,335 Days
• Field of Search: H04/N.1387, 358/538-540, 358/501, 358/450, 358/453, 358/458, 358/447-448, 382/210, 382/268, 382/284
• US Class Current: 358/3.28
• CPC Class Codes: H04N 1/32203 Spatial or amplitude domain methods H04N1/32309 takes precedence
• CPC Class Codes: H04N 1/32208 involving changing the magnitude of selected pixels, e.g. overlay of information or super-imposition H04N1/32219, H04N1/32224 take precedence
• CPC Class Codes: H04N 1/32229 with selective or adaptive application of the additional information, e.g. in selected regions of the image H04N1/32213 takes precedence
• CPC Class Codes: H04N 1/32251 in multilevel data, e.g. greyscale or continuous tone data
• CPC Class Codes: H04N 2201/3233 of authentication information, e.g. digital signature, watermark
• CPC Class Codes: H04N 2201/327 which are undetectable to the naked eye, e.g. embedded codes
• CPC Class Codes: H04N 2201/328 Processing of the additional information

Abstract

The subject matter of the invention is to add information to image data of multicolor image and monochromatic image. An image processing apparatus capable of adding information on raw data performs a dispersion conversion on the spectrum of the additional information by multiplying a code sequence of the PN sequence generator 114 by the additional data which is inputted from the input terminal 111 and converted into serial data in P/S converter 112. At this time, the data sequence transmitted from the image signal processor 102 to the printer engine 107 is converted by the scan converter 109 to correspond to the spatial axis for desperation. The converted data sequence is added to the output from the adder 113 by the adder 110, and reconverted to the original scan by the scan inverter 115.

Claims

1. An image processing apparatus comprising:

input means for inputting digital image data substantially representing an original image, said digital image data including predetermined additional information previously added to a spatial frequency component of said original image, wherein the presence of said predetermined additional information is difficult to discriminate with human eyes; and

extraction means for extracting said predetermined additional information from digital image data inputted by said input means by subjecting said digital image data to image-processing, said extraction means including means for multiplying the digital image data by a timing signal to cause the digital image data to have the spectrum of the original image.

2. An image processing apparatus according to claim 1, wherein said input means reads an image formed on a recording medium to generate digital image data.

3. An image processing apparatus according to claim 1, wherein said extraction means extracts said predetermined additional information in a block of predetermined data.

4. An image processing apparatus according to claim 1, wherein a spectrum characteristic of said digital image data is converted in said image processing.

5. An image processing method comprising:

an input step of inputting digital image data substantially representing an original image, the digital image data including predetermined additional information previously added to a spatial frequency component of the original image, wherein the presence of the predetermined additional information is difficult to discriminate with human eyes; and

an extraction step of extracting the predetermined additional information from digital image data inputted in said input step by subjecting the digital image data to image-processing, said extraction step comprising a step of multiplying the digital image data by a timing signal to cause the digital image data to have the spectrum of the original image.

6. An image processing apparatus comprising:

inputting means for inputting an original image;

first adding means for adding first additional information to the inputted original image so that the first additional information is difficult to discriminate with human eyes; and

second adding means for adding second additional information to the image to which the first additional information is added by the first adding means so that the second additional information is difficult to discriminate with human eyes,

wherein each of said first and second adding means includes a spatial spectrum converter circuit that converts a spatial spectrum of the first or second additional information, and the first and second additional information are processed to provide a spatial spectrum conversion and then are added to a spatial frequency component of the original image.

7. An image processing apparatus according to claim 6, wherein said first and second additional information are different from each other.

8. An image processing apparatus according to claim 6, wherein said first and second addition information are inputted at respective input terminals which are different from each other.

9. An image processing apparatus according to claim 6, wherein said second adding means adds said second additional information onto image data of an image region in a multiplexed manner where said first additional information has been added by the said first adding means.

10. An image processing apparatus according to claim 6, wherein said second adding means adds said second additional information so that both said first and second additional information are restored from the image to which said first and second additional information have been added.

11. An image processing apparatus according to claim 6, further comprising a printing means for printing an image generated by said second adding means.

12. An image processing method comprising the steps of:

inputting an original image;

firstly adding first additional information, using first adding means, to the inputted original image so that the first additional information is difficult to discriminate with human eyes; and

secondly adding second additional information, using second adding means, to the image to which the first additional information is added in the first adding step so that the second additional information is difficult to discriminate with human eyes,

wherein each of the first and second adding means includes a spatial spectrum converter circuit that converts a spatial spectrum of the first or second additional information, and the first and second additional information are processed to provide a spatial spectrum conversion and then are added to a spatial frequency component of the original image.

13. An image processing apparatus comprising:

an input terminal to input digital image data substantially representing an original image comprising a plurality of spatial frequency components, the digital image data including predetermined additional information previously added to one spatial frequency component of said original image, wherein the presence of said predetermined additional information is difficult to discriminate with human eyes; and

an extraction circuit that extracts the predetermined additional information from the input digital image data, said extraction circuit including a multiplier to multiply the digital image data by a timing signal selected to convert the digital image data to data having the spectrum of the original image.

14. An apparatus according to claim 13, wherein said extraction circuit further comprises a modulation signal generator that outputs a signal having the same timing as the modulation signal used to add the predetermined additional information to the original image.

15. An apparatus according to claim 14, wherein said extraction circuit further comprises a block divider circuit that performs blocking of the digital image data, before the image data is multiplied by the timing signal, to alter the order of the image data sequence so as to have an identical space as used when adding the predetermined additional information to the original image.

16. An apparatus according to claim 15, wherein said extraction circuit further comprises a phase shifter and a synchronization detector, wherein said synchronization detector controls a synchronization state by outputting control signals to shift the phase of blocking performed in said block divider circuit and to shift the phase of the signal output by said modulating signal generator, using said phase shifter, to select the timing signal for input to said multiplier.

17. An image processing apparatus comprising:

an input terminal to input data of an original image;

a first adder circuit that adds first additional information to the inputted original image data in a manner that makes the first additional information difficult to discriminate with human eyes; and

a second adder circuit that adds second additional information to the image data to which the first additional information has been added by the first adder circuit, in a manner that makes the second additional information difficult to discriminate with human eyes,

wherein each of said first and second adder circuits includes a spatial spectrum converter circuit that converts a spatial spectrum of additional information before adding it to a spatial frequency component of the image data.

18. An apparatus according to claim 17, wherein said spatial spectrum converter circuit comprises a modulation signal generator and a multiplier that multiplies the additional information by a an output signal of said modulation signal generator.

19. An apparatus according to claim 18, wherein said at least one adder circuit further includes a block divider circuit that converts a sequence of the image data before said at least one adder circuit adds the additional information to the image data.