Method for embedding digital information in an image

Claim 1

A method of embedding digital data in a source image, comprising the steps of: a) generating a multi-level data image representing the digital data; b) convolving the multi-level data image with a variable frequency encoding carrier image to produce a frequency dispersed data image; wherein the variable frequency encoding carrier image is generated by the steps of: b1) providing a 1-dimensional variable frequency carrier signal, wherein the 1-dimensional variable frequency carrier signal is a linear chip signal defined by: ##EQU3## where r is the distance in units of pixels, f min is the minimum frequency of the chirp, f max is the maximum frequency of the chirp, and L is the total length of the chirp in the units of pixels; and b2) converting the 1-dimensional variable frequency carrier signal to a 2-dimensional variable frequency carrier signal using a rotational sweep; and c) adding the frequency dispersed data image to the source image to produce a source image containing embedded data.

Claim 2

A method of embedding digital data in a source image, comprising the steps of: a) generating a multi-level data image representing the digital data; b) convolving the multi-level data image with a variable frequency encoding carrier image to produce a frequency dispersed data image; wherein the variable frequency encoding carrier image is generated by the steps of: b1) providing a 1-dimensional variable frequency carrier signal, wherein the 1-dimensional variable frequency carrier signal is a linear chip signal defined by: ##EQU3## where r is the distance in units of pixels, f min is the minimum frequency of the chirp, f max is the maximum frequency of the chirp, and L is the total length of the chirp in the units of pixels; and b2) converting the 1-dimensional variable frequency carrier signal to a 2-dimensional variable frequency carrier signal using a rotational sweep; and c) adding the frequency dispersed data image to the source image to produce a source image containing embedded data.

Claim 3

A method of embedding digital data in a source image, comprising the steps of: a) generating a multi-level data image representing the digital data; b) convolving the multi-level data image with a variable frequency encoding carrier image to produce a frequency dispersed data image; wherein the variable frequency encoding carrier image is generated by the steps of: b1) providing a 1-dimensional variable frequency carrier signal, wherein the 1-dimensional variable frequency carrier signal is a logarithmic chirp signal defined by: ##EQU4## where r is the distance in units of pixels, f min is the minimum frequency of the chirp, f max is the maximum frequency of the chirp, and L is the total length of the chirp in the units of pixels; b2) converting the 1-dimensional variable frequency carrier signal to a 2-dimensional variable frequency carrier signal using a rotational sweep; and c) adding the frequency dispersed data image to the source image to produce a source image containing embedded data.

Claim 4

A method of embedding digital data in a source image, comprising the steps of: a) generating a multi-level data image representing the digital data; b) convolving the multi-level data image with a variable frequency encoding carrier image to produce a frequency dispersed data image; wherein the variable frequency encoding carrier image is generated by the steps of: b1) providing a 1-dimensional variable frequency carrier signal, wherein the 1-dimensional variable frequency carrier signal is a logarithmic chirp signal defined by: ##EQU4## where r is the distance in units of pixels, f min is the minimum frequency of the chirp, f max is the maximum frequency of the chirp, and L is the total length of the chirp in the units of pixels; b2) converting the 1-dimensional variable frequency carrier signal to a 2-dimensional variable frequency carrier signal using a rotational sweep; and c) adding the frequency dispersed data image to the source image to produce a source image containing embedded data.

Claim 5

A method of embedding digital data in a source image, comprising the steps of: a) generating a multi-level data image representing the digital data; b) convolving the multi-level data image with a variable frequency encoding carrier image to produce a frequency dispersed data image; c) adding the frequency dispersed data image to the source image to produce a source image containing embedded data; d) cross correlating the source image containing embedded data with a variable frequency decoding carrier image to recover the data image; e) extracting the digital data from the recovered data image; and f) locating a subset of the source image containing embedded data having the lowest high-frequency component variance and cross correlating the subset with the decoding carrier image.

Claim 6

A method of embedding digital data in a source image, comprising the steps of: a) generating a multi-level data image representing the digital data; b) convolving the multi-level data image with a variable frequency encoding carrier image to produce a frequency dispersed data image; c) adding the frequency dispersed data image to the source image to produce a source image containing embedded data; d) cross correlating the source image containing embedded data with a variable frequency decoding carrier image to recover the data image; e) extracting the digital data from the recovered data image; and f) locating a subset of the source image containing embedded data having the lowest high-frequency component variance and cross correlating the subset with the decoding carrier image.

Claim 7

A method of embedding digital data in a source image, comprising the steps of: a) generating a multi-level data image representing the digital data; b) convolving the multi-level data image with a variable frequency encoding carrier image to produce a frequency dispersed data image; and c) adding the frequency dispersed data image to the source image to produce a source image containing embedded data, wherein the step of adding is performed by optical techniques, and wherein the variable frequency dispersed data image is added to the source image in a photographic printer by placing a transparency having the frequency dispersed image in the film gate of the printer.

Claim 8

A method of embedding digital data in a source image, comprising the steps of: a) generating a multi-level data image representing the digital data; b) convolving the multi-level data image with a variable frequency encoding carrier image to produce a frequency dispersed data image; and c) adding the frequency dispersed data image to the source image to produce a source image containing embedded data, wherein the step of adding is performed by optical techniques, and wherein the variable frequency dispersed data image is added to the source image in a photographic printer by placing a transparency having the frequency dispersed image in the film gate of the printer.

Claim 9

A method of embedding digital data in a source image, comprising the steps of: a) generating a multi-level data image representing the digital data; b) convolving the multi-level data image with a variable frequency encoding carrier image to produce a frequency dispersed data image; and c) adding the frequency dispersed data image to the source image to produce a source image containing embedded data, wherein the step of adding is performed by optical techniques, and wherein the frequency dispersed data image is added to the source image in a photographic printer by pre-exposing photographic paper used in the printer with the frequency dispersed image.

Claim 10

A method of embedding digital data in a source image, comprising the steps of: a) generating a multi-level data image representing the digital data; b) convolving the multi-level data image with a variable frequency encoding carrier image to produce a frequency dispersed data image; and c) adding the frequency dispersed data image to the source image to produce a source image containing embedded data, wherein the step of adding is performed by optical techniques, and wherein the frequency dispersed data image is added to the source image in a photographic printer by pre-exposing photographic paper used in the printer with the frequency dispersed image.

Claim 11

A method of embedding digital data in a source image, comprising the steps of: a) generating a multi-level data image representing the digital data; b) convolving the multi-level data image with a variable frequency encoding carrier image to produce a frequency dispersed data image; and c) adding the frequency dispersed data image to the source image to produce a source image containing embedded data, wherein the variable frequency encoding carrier image is generated by the steps of: b1) providing a 1-dimensional variable frequency carrier signal; and b2) converting the 1-dimensional variable frequency carrier signal to a 2-dimensional variable frequency carrier signal using a rotational sweep; and c) applying a tapered weighting function to the variable frequency carrier signal.

Claim 12

A method of embedding digital data in a source image, comprising the steps of: a) generating a multi-level data image representing the digital data; b) convolving the multi-level data image with a variable frequency encoding carrier image to produce a frequency dispersed data image; and c) adding the frequency dispersed data image to the source image to produce a source image containing embedded data, wherein the variable frequency encoding carrier image is generated by the steps of: b1) providing a 1-dimensional variable frequency carrier signal; and b2) converting the 1-dimensional variable frequency carrier signal to a 2-dimensional variable frequency carrier signal using a rotational sweep; and c) applying a tapered weighting function to the variable frequency carrier signal.

Claim 13

A method of embedding digital data in a source image, comprising the steps of: a) generating a multi-level data image representing the digital data; b) convolving the multi-level data image with a variable frequency encoding carrier image to produce a frequency dispersed data image; and c) adding the frequency dispersed data image to the source image to produce a source image containing embedded data, wherein the adding step is performed optically, and wherein the step of adding the frequency dispersed data image to the source image utilizes a scaling factor dependent on film characteristics.

Claim 14

A method of embedding digital data in a source image, comprising the steps of: a) generating a multi-level data image representing the digital data; b) convolving the multi-level data image with a variable frequency encoding carrier image to produce a frequency dispersed data image; and c) adding the frequency dispersed data image to the source image to produce a source image containing embedded data, wherein the adding step is performed optically, and wherein the step of adding the frequency dispersed data image to the source image utilizes a scaling factor dependent on film characteristics.

Claim 15

A method of embedding digital data in a source image, comprising the steps of: a) generating a multi-level data image representing the digital data; b) convolving the multi-level data image with a variable frequency encoding carrier image to produce a frequency dispersed data image; and c) adding the frequency dispersed data image to the source image to produce a source image containing embedded data, wherein the adding step is performed optically, and wherein the adding step is performed by contact exposing a transparency bearing the frequency dispersed data image onto photographic paper.

Claim 16

A method of embedding digital data in a source image, comprising the steps of: a) generating a multi-level data image representing the digital data; b) convolving the multi-level data image with a variable frequency encoding carrier image to produce a frequency dispersed data image; and c) adding the frequency dispersed data image to the source image to produce a source image containing embedded data, wherein the adding step is performed optically, and wherein the adding step is performed by contact exposing a transparency bearing the frequency dispersed data image onto photographic paper.

Claim 17

A method of embedding digital data in a source image, comprising the steps of: a) generating a multi-level data image representing the digital data; b) convolving the multi-level data image with a variable frequency encoding carrier image to produce a frequency dispersed data image; and c) adding the frequency dispersed data image to the source image to produce a source image containing embedded data, wherein the adding step is performed optically, and wherein the adding step is performed by simultaneously exposing the source image and the frequency dispersed data image onto photographic paper in photographic printer.

Claim 18

A method of embedding digital data in a source image, comprising the steps of: a) generating a multi-level data image representing the digital data; b) convolving the multi-level data image with a variable frequency encoding carrier image to produce a frequency dispersed data image; and c) adding the frequency dispersed data image to the source image to produce a source image containing embedded data, wherein the adding step is performed optically, and wherein the adding step is performed by simultaneously exposing the source image and the frequency dispersed data image onto photographic paper in photographic printer.

Claim 19

A method of embedding digital data in a source image, comprising the steps of: a) generating a multi-level data image representing the digital data; b) convolving the multi-level data image with a variable frequency encoding carrier image to produce a frequency dispersed data image; and c) adding the frequency dispersed data image to the source image to produce a source image containing embedded data, wherein the adding step is performed optically, and wherein the adding step is performed by affixing a transparency bearing the frequency dispersed data image onto the source image.

Claim 20

A method of embedding digital data in a source image, comprising the steps of: a) generating a multi-level data image representing the digital data; b) convolving the multi-level data image with a variable frequency encoding carrier image to produce a frequency dispersed data image; and c) adding the frequency dispersed data image to the source image to produce a source image containing embedded data, wherein the adding step is performed optically, and wherein the adding step is performed by affixing a transparency bearing the frequency dispersed data image onto the source image.

Claim 21

A method of embedding digital data in a source image, comprising the steps of: a) generating a multi-level data image representing the digital data; b) convolving the multi-level data image with a variable frequency encoding carrier image to produce a frequency dispersed data image; and c) adding the frequency dispersed data image to the source image to produce a source image containing embedded data; d) cross correlating the source image containing embedded data with a variable frequency decoding carrier image to recover the data image; and e) extracting the digital image from the recovered data image; wherein the recovered data image has rows and columns of values, further comprising the steps of: e1) finding the difference between the minimum and maximum values for each row of the recovered data image to produce row difference values; e2) finding the difference between the minimum and maximum values for each column of the recovered data image to produce column difference values; e3) finding the n highest difference values for the rows and saving the indices of these rows, where n is determined from the size of the multi-level data message; e4) finding the n highest difference values for the columns and saving the indices of these columns, where n is determined from the size of the multi-level data message; and e5) locating data centers in the recovered data image by intersecting the saved rows and columns.

Claim 22

A method of embedding digital data in a source image, comprising the steps of: a) generating a multi-level data image representing the digital data; b) convolving the multi-level data image with a variable frequency encoding carrier image to produce a frequency dispersed data image; and c) adding the frequency dispersed data image to the source image to produce a source image containing embedded data; d) cross correlating the source image containing embedded data with a variable frequency decoding carrier image to recover the data image; and e) extracting the digital image from the recovered data image; wherein the recovered data image has rows and columns of values, further comprising the steps of: e1) finding the difference between the minimum and maximum values for each row of the recovered data image to produce row difference values; e2) finding the difference between the minimum and maximum values for each column of the recovered data image to produce column difference values; e3) finding the n highest difference values for the rows and saving the indices of these rows, where n is determined from the size of the multi-level data message; e4) finding the n highest difference values for the columns and saving the indices of these columns, where n is determined from the size of the multi-level data message; and e5) locating data centers in the recovered data image by intersecting the saved rows and columns.