Embedding encoded information in an iconic version of a text image

• US 5,761,686 A
• Filed: 06/27/1996
• Issued: 06/02/1998
• Est. Priority Date: 06/27/1996
• Status: Expired due to Fees

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Bloomberg, Dan S.
• Primary Examiner(s): Burwell, Joseph R.
• Application Number:
  US08/671,423
• Time in Patent Office: 705 Days
• Field of Search: 395/788-791, 395/761, 382/180, 382/232, 382/243, 382/112, 707/526-529
• US Class Current: 715/234
• CPC Class Codes: G06T 1/0021 Image watermarking
• CPC Class Codes: G06T 2201/0051 Embedding of the watermark in the spatial domain
• CPC Class Codes: G06T 2201/0061 Embedding of the watermark in each block of the image, e.g. segmented watermarking
• CPC Class Codes: G06T 3/04 Context-preserving transformations, e.g. by using an importance map panospheric to cylindrical image transformations G06T3/12

Abstract

An encoding operation encodes binary data that is then embedded in an iconic, or size-reduced, version of an original text image, in a position in the iconic image that replaces a text portion in the original text image. The encoding operation produces rectangular blocks that have a foreground color and size dimensions proportional to the iconic image so that when placed in the iconic image in horizontal lines, the blocks appear to a viewer to be representative of the text portion of the original image that they replace. Exemplary encoding operations are described, including operations based on run-length limited encoding. A second message may be encoded in the background color regions that separate the blocks. The message carried by the binary data may be any information suitable for a particular application, and need not be restricted to information about or related to the original image. The encoding operation is designed to be robust for decoding purposes regardless of the resolution at which a copy of the iconic image is subsequently rendered. The iconic image may be printed in a suitable place (e.g., the margin or other background region) in the original text image so that a text image so annotated will then always carry the embedded data in subsequent copies made from the annotated original. The iconic image alone may also be used in printed form or as part of a graphical user interface as a surrogate for the original text image in a variety of applications.

Claims

1. A method for operating a processor-controlled machine to encode binary data in an iconic version of an input text image;

the machine including a signal source for receiving data;

memory for storing data; and

a processor connected for accessing instruction data stored in the memory for operating the machine;

the processor being further connected for receiving data from the signal source; and

connected for storing data in the memory;

the method comprising;

receiving image definition data defining an input text image from the signal source;

the input text image having a characteristic page layout appearance perceptible to a human viewer of the input text image when rendered and displayed for viewing;

the input text image including at least one image region including image definition data defining text, referred to as an original text region;

receiving, from the signal source, binary data indicating a message to be encoded;

receiving image position input data from the signal source;

performing an encoding operation using the binary data and using the image position input data to produce image definition data defining a plurality of rectangular blocks each having a foreground color;

the encoding operation mapping a portion of the binary data to a respective rectangular block referred to as an encoded data block;

performing an image reduction operation using the input text image to produce image definition data defining a reduced version of the input text image, referred to as an iconic image;

the iconic image having the characteristic page layout appearance of the input text image when rendered for display and viewed by the user; and

producing the iconic image including the encoded data blocks;

the encoded data blocks being positioned in place of a reduced version of the original text region in the iconic image version of the input text image;

the encoded data blocks each having size dimensions suitable for inclusion in the iconic image, and being arranged in horizontal lines separated vertically by image regions of a background color.

2. The method of claim 1 for operating a processor-controlled machine to encode binary data in an iconic version of an input text image wherein the encoding operation encodes, for all binary data to be encoded, a fixed-bit portion of the binary data into a single encoded data block of a foreground color having a characteristic property determined by a value computed using the fixed-bit portion of the binary data.

3. The method of claim 2 wherein the characteristic property is a size dimension of the encoded data block.

4. The method of claim 3 wherein the size dimension is a length of the encoded data block.

5. The method of claim 3 wherein the size dimension is a height of the encoded data block when positioned in a horizontal line with respect to a baseline of the horizontal line.

6. The method of claim 2 wherein the characteristic property is a vertical position of an encoded data block when positioned in a horizontal line with respect to a baseline of the horizontal line.

7. The method of claim 2 wherein the encoding operation further encodes second binary data in regions of background color positioned between encoded data blocks on a horizontal line.

8. The method of claim 7 wherein the second binary data indicates information for use in decoding the message encoded in the encoded data blocks.

9. The method of claim 8 wherein the information for use in decoding the message is error detection information.

10. The method of claim 7 wherein the second binary data indicates a second message.

11. The method of claim 1 for operating a processor-controlled machine to encode binary data in an iconic version of an input text image wherein the encoding operation maps fixed bit sized portions of the binary data to be encoded to respective length values using a numerical value computed from each fixed bit sized portion of the binary data;

each respective length value being used to determine the horizontal length in the iconic image of a respective encoded data block.

12. The method of claim 1 for operating a processor-controlled machine to encode binary data in an iconic version of an input text image wherein the encoding operation encodes, for all of the binary data to be encoded, a variable bit sized portion of the binary data into one of a plurality of specific sequences of output message bits including both foreground and background colors;

the plurality of specific sequences of output message bits being designed to produce varying-length encoded data blocks of foreground colors.

13. The method of claim 12 wherein the encoding operation uses a run-length limited coding scheme to encode the variable bit sized portions of the binary data into specific sequences of output message bits including both foreground and background colors.

14. The method of claim 1 for operating a processor-controlled machine to encode binary data in an iconic version of an input text image wherein the encoding operation uses a run-length limited coding scheme to encode the binary data into the encoded data blocks.

15. The method of claim 1 for operating a processor-controlled machine to encode binary data in an iconic version of an input text image wherein producing the iconic image including the encoded data blocks includes inserting image definition data defining a marking block in an iconic image position on the same horizontal line as are positioned encoded data blocks;

the marking block marking the location of encoded data blocks for use by a subsequently performed decoding operation.

16. The method of claim 1 for operating a processor-controlled machine to encode binary data in an iconic version of an input text image wherein performing the encoding operation further includes producing second binary data indicating a second message to be encoded;

the second message indicating information about the encoded data blocks;

the encoding operation further encoding the second binary data with the binary data to be encoded;

the second binary data encoded by the encoding operation being available in the iconic image to a decoding operation for use in decoding the encoded data blocks to retrieve the message indicated by the binary data.

17. The method of claim 1 for operating a processor-controlled machine to encode binary data in an iconic version of an input text image wherein the image position input data indicates coordinates of a bounding box in the input text image containing the at least one original text region;

the image reduction operation determining positions of the encoded data blocks in the iconic image using the coordinates of the bounding box in the input text image.

18. The method of claim 17 wherein the coordinates of the bounding box containing the original text region are produced by performing an image segmentation operation using the input text image.

19. The method of claim 1 for operating a processor-controlled machine to encode binary data in an iconic version of an input text image wherein the image position input data indicates coordinates in the iconic image of a bounding box to be used to position the encoded data blocks in the iconic image.

20. An article of manufacture for use in a machine that includes a memory device for storing data;

a storage medium access device for accessing a medium that stores data; and

a processor connected for accessing the data stored in the memory device and for receiving data from the storage medium access device;

the article comprising;

a data storage medium that can be accessed by the storage medium access device when the article is used in the machine; and

data stored in the data storage medium so that the storage medium access device can provide the stored data to the processor when the article is used in the machine;

the stored data comprising instruction data indicating instructions the processor can execute;

the processor, in executing the instructions, receiving image definition data defining an input text image from the signal source;

the input text image having a characteristic page layout appearance perceptible to a human viewer of the input text image when rendered and displayed for viewing;

the input text image including at least one image region including image definition data defining text, referred to as an original text region;

the processor, further in executing the instructions, receiving binary data indicating a message to be encoded;

the processor, further in executing the instructions, receiving image position input data;

the processor, further in executing the instructions, performing an encoding operation using the binary data and using the image position input data to produce image definition data defining a plurality of rectangular blocks each having a foreground color;

the encoding operation mapping a portion of the binary data to a respective rectangular block referred to as an encoded data block;

the processor, further in executing the instructions, performing an image reduction operation using the input text image to produce image definition data defining a reduced version of the input text image, referred to as an iconic image;

the iconic image having the characteristic page layout appearance of the input text image when rendered for display and viewed by the user;

the processor, still further in executing the instructions, producing the iconic image including the encoded data blocks;

the encoded data blocks being positioned in place of a reduced version of the original text region in the iconic image version of the input text image;

the encoded data blocks each having size dimensions suitable for inclusion in the iconic image, and being arranged in horizontal lines separated vertically by image regions of a background color.