Encoding and decoding a message within an image

• US 6,256,398 B1
• Filed: 08/22/1998
• Issued: 07/03/2001
• Est. Priority Date: 08/22/1998
• Status: Expired due to Term

• Current Assignee: Celebrate International LLC
• Original Assignee: Kenneth H.P. Chang
• Inventors: Chang, Kenneth H. P.
• Primary Examiner(s): Mancuso, Joseph
• Assistant Examiner(s): TABATABAI, ABOLFAZL
• Application Number:
  US09/138,591
• Time in Patent Office: 1,046 Days
• Field of Search: 382/100, 382/270, 382/317, 382/159, 707/513, 235/462, 235/494, 395/200.47, 455/6.2
• US Class Current: 382/100
• CPC Class Codes: G06K 19/06046 Constructional details
• CPC Class Codes: G06K 7/14 using light without selection of wavelength, e.g. sensing reflected white light G06K7/10831 - G06K7/1097 take precedence
• CPC Class Codes: G06K 7/143 Glyph-codes

Abstract

A method for decoding a message embedded in a pattern of pixels. The method includes the steps of determining the pixel values for pixels from the pattern of pixels, determining binary values from the pixel values for pixels from the pattern of pixels; and determining the embedded message from the binary values. The pixels have a range of pixel values between a maximum and a minimum. The pixels are divided into cells each having glyph cell and background pixels. The binary value of a glyph pixel is determined by the contrast the glyph pixel has with its background pixels. The method can be used to decode embedded web-site address from an image with a foreground image and the embedded web-site address.

Claims

1. A device for loading a web-site address into a web browser for connecting to the web-site, comprising:

(a) reader for receiving light from a pattern of pixels and determining pixel value of each pixel, said pattern of pixels constituting a foreground visual image that conveys information to an observer; and

(b) processor having a program of code means readable by the processor to recover an embedded web-site address from the pattern of pixels, the program comprising;

(i) code means for determining the embedded web-site address by determining binary values using contrast of brightness to compare pixel values of selected pixels to the pixel values of pixels neighboring thereto in the pattern of pixels; and

(ii) code means for loading the web-site address onto the web browser for connecting to the web-site according to the web-site address.

2. The device according to claim 1 wherein the reader comprises a light source for illuminating the pattern of pixels to provide light pattern of different pixel values and the reader comprises an image sensor to record the light.

3. The device according to claim 1 wherein the code means for determining the embedded web-site address divides the pattern of pixels into cells each containing a matrix of pixels to determine said binary values.

4. The device according to claim 3 wherein the visual image shows text or an object and wherein the code means for determining the embedded web-site address determines a binary value of a pixel in a cell via comparing its pixel value in relation to a value derived from the pixel values of pixels neighboring thereto in the cell.

5. The device according to claim 4 wherein the code means for determining the embedded we-site address determines the contrast of between brightness of a glyph pixel and average brightness derived from background in the cell to find the binary value represented by the glyph pixel.

6. The device according to claim 3 wherein the code means for determining the embedded web-site address further compares data from pixels in one area of the light pattern to data from pixels in another area of the light pattern for symmetry to determine the embedded web-site address.

7. The device according to claim 3 wherein the code means for determining the embedded web-site address separates pixels in each cell into one or more glyph pixels and background pixels and determines said binary values via determining the relationship of data of a glyph pixel in one cell to data of glyph pixel of another cell.

8. The device according to claim 3 further comprising a computer running the web browser and a transmitter for transmitting electromagnetic signals representing web-site address to the computer to direct the web browser to connect to the web site.

9. A method for loading a URL address into a web browser, comprising:

(a) receiving light from a display showing a pattern of pixels and determining pixel value of each pixel, said pattern of pixels constituting a foreground visual image that conveys information to an observer;

(b) recovering an embedded URL address by determining binary values using contrast of brightness to compare pixel values of selected pixels to the pixel values of pixels neighboring thereto in the pattern of pixels; and

(c) loading the URL address into the web browser for connecting to the web site according to the URL address.

10. The method according to claim 9 further comprising arranging the pixels in said pattern of pixels into cells each having a matrix of pixels, each cell having one or more glyph pixels and neighboring background pixels;

and for each glyph pixel determining the binary value of the glyph pixel based on contrasting the glyph pixel'"'"'s brightness to a value derived from the brightness of the background pixels in the cell, and wherein the visual image shows text or an object.

11. The method according to claim 10 wherein the contrasting step comprises contrasting a pixel to an average deriving from pixels neighboring thereto in a cell.

12. The method according to claim 11 wherein the determining binary values via contrasting step comprises:

for each glyph pixel determining the average pixel value of its background pixels and calculating the difference between the glyph pixel'"'"'s pixel value and its average background pixel value; and

determining the binary value to be a first binary value if said difference is larger than a threshold and determining the binary value to be a second binary value if said difference is smaller than the threshold.

13. The method according to claim 11 whereas determining binary values further comprising dividing the pixels in cells via transforming the pixel values of the pixels into a glyph map by substantially removing the foreground image.

14. The method according to claim 13 whereas the step of recovering an embedded URL address further comprising substantially removing the foreground image to form the glyph map by determining for all pixels in the block the absolute value of the difference between a pixel and its neighboring pixels.

15. The method according to claim 14 whereas the step of recovering an embedded URL address by determining binary values further comprising recovering a data stream including data of the image and data of the URL address and recovering a synchronization stream directing the interpretation of data in the data stream wherein the sync stream interleaves the data stream.

16. The method according to claim 15 whereas the step of recovering an embedded URL address by determining binary values further comprising determining a synchronization stream having a forward synchronization portion and a backward synchronization portion in symmetry therewith.

17. The method according to claim 13 whereas the step of recovering an embedded URL address further comprising determining cell size by taking pixels of local maximum pixel values (local max pixel) and determining a statistical distance from such local max pixels to neighboring local max pixels to indicate the distance from glyph pixel to neighboring glyph pixels.

18. The method according to claim 17 whereas the step of recovering an embedded URL address further comprising determining a grid of the location of the glyph pixels by rendering a more uniform pattern of pixel value for glyph pixels by iteratively deriving an updated pixel value of each local max pixel from a group containing said local max pixel and its surrounding local max pixels.

19. The method according to claim 9 further comprising comparing data from pixels in one area of the light pattern to data from pixels in another area of the light pattern for symmetry to determine the embedded web-site address.

20. A method for decoding a message embedded in a pattern of pixels, comprising:

(a) determining the pixel values based on brightness for pixels from the pattern of pixels, said pattern of pixels constituting a foreground visual image that conveys information to an observer;

(b) determining binary values from the pixel values for pixels from the pattern of pixels via contrasting the brightness of selected pixels to the brightness of pixels neighboring thereto; and

(c) determining the embedded message from the binary values.

21. The method according to claim 20 wherein the pixels have a range of pixel values between a maximum and a minimum and further the step of determining binary values comprising:

(a) for each cell, determining the pixel value of a selected pixel based on brightness thereof and determining the average pixel value of the background pixels based on the brightness of said background pixels;

(b) for each cell finding the difference between the pixel value of the selected pixel in the cell and an average derived from pixel values of the cells neighboring to the selected pixel and determining the binary value to be one binary value if the difference is larger than a threshold and determining the binary value to be another binary value if the difference is less than the threshold.

22. The method according to claim 20 further comprising comparing data from pixels in one area of the light pattern to data from pixels in another area of the light pattern for symmetry to determine the embedded message.

23. A method for embedding a message into an initial image, comprising:

(a) determining dimensions of a block of pixels for displaying the initial image, said initial image conveying information to an observer; and

(b) determining a data stream having data of the embedded message in conjunction with data of the initial image such that binary values of the data stream can be represented using contrast of brightness of pixels in the block, wherein a resulting image containing the embedded message is substantially similar to the initial image that the resulting image has no substantial visually recognizable irregular distribution of pixels caused by the embedded message.

24. An optically readable two-dimensional coding system, comprising:

a two dimensional pattern of pixels constituting a foreground visual image that conveys information to an observer, wherein the pixels have pixel values and are divided into tiles of cells, substantially all the tiles having a synchronization cell neighbored by a plurality of data cells;

the data cells containing factual data encoded using contrast of brightness of pixels and the synchronization cells indicating how the factual data are to be interpreted based on the position of the data cells;

the synchronization cells substantially interleaving the data cells throughout the two dimensional pattern of pixels.

25. A method for representing binary values of binary bits with a display of pattern of pixels constituting a foreground visual image, comprising:

(a) arranging the pixels into cells each having a matrix of pixels, each cell having one or more glyph pixels and neighboring background pixels, said pattern of pixels constituting a foreground visual image that conveys information to an observer; and

(b) for each cell, setting pixel values to the pixels based on brightness thereof and if the contrast between the brightness of the glyph pixel and that of the background pixels is small assigning a new pixel value to each glyph pixel to render a high contrast between the glyph pixel'"'"'s old pixel value and new pixel value to represent a selected binary value whereas to not assign a new pixel value to the glyph pixel so as to not render a high contrast between the glyph pixel'"'"'s new pixel value and old pixel value to represent a second selected binary value.

26. A method for two dimensional coding, comprising:

(a) providing a block of pixels to show a foreground visual image with an embedded message, said visual image conveying information to an observer;

(b) dividing the pixels into tiles of cells, substantially all the tiles having a synchronization cell neighbored by a plurality of data cells;

the data cells for containing factual data for the embedded message and the synchronization cells for indicating how the factual data are to be interpreted based on the position of the data cells;

the synchronization cells substantially interleaving the data cells throughout the two dimensional pattern of pixels; and

(c) representing the binary values of the synchronization cells and data cells by varying the pixel values for brightness contrasting such that the embedded message does not obtrusively distort the foreground visual image and such that there is no optically readable two dimensional reference structure.

27. A method for two dimensional encoding a message, comprising:

(a) providing a block of pixels showing a foreground visual image that conveys information to an observer;

(b) dividing the pixels into tiles of cells such that substantially all of the tiles having the same number of data cells, and dividing the data cells to include a first group and a second group to show a message stream representing the message; and

(c) by contrasting brightness representing the bit values of the message stream such that each bit of the message stream is represented by the relationship between a binary value of a cell of the first group and a binary value of a cell of the second group without obtrusively distorting the foreground visual image and such that there is no optically readable two dimensional reference structure.

28. The method according to claim 27 wherein the binary values of the cells of the first group are the inverse of the cells of the second group.

29. The method according to claim 27 wherein the first group is geometrically symmetric to the second group.