Watermarking scheme for image authentication

Claim 1

A method for applying a digital watermark to an image, comprising the steps of: (A) deriving from the image a plurality of component images, wherein each component image contains coefficients; (B) providing at least one look-up table containing a plurality of coefficients and corresponding values, wherein at least some of the look-up table coefficients match coefficients in said component images; (C) embedding said watermark in said image by performing the following substeps for at least some of said component images: (1) selecting a coefficient into which a marking value, representative of a corresponding portion of the watermark, is to be embedded; (2) using the value of the selected coefficient to identify a corresponding value in said look-up table(s); (3) leaving the selected coefficient unchanged if the corresponding value is the same as the marking value; and (4) changing the selected coefficient if the corresponding value is different from the marking value; further comprising the step of identifying selected coefficients as being unembeddable, wherein said unembeddable coefficients are not employed in step (C) to embed marking values, and wherein some of said coefficients are identified as DC coefficients, and said DC coefficients are considered unembeddable; and further comprising selecting a threshold value, wherein coefficients having a value below said threshold value are considered small valued and thus unembeddable.

Claim 2

A method for applying a digital watermark to an image, comprising the steps of: (A) deriving from the image a plurality of component images, wherein each component image contains coefficients; (B) providing at least one look-up table containing a plurality of coefficients and corresponding values, wherein at least some of the look-up table coefficients match coefficients in said component images; (C) embedding said watermark in said image by performing the following substeps for at least some of said component images: (1) selecting a coefficient into which a marking value, representative of a corresponding portion of the watermark, is to be embedded; (2) using the value of the selected coefficient to identify a corresponding value in said look-up table(s); (3) leaving the selected coefficient unchanged if the corresponding value is the same as the marking value; and (4) changing the selected coefficient if the corresponding value is different from the marking value; further comprising the step of identifying selected coefficients as being unembeddable, wherein said unembeddable coefficients are not employed in step (C) to embed marking values, and wherein some of said coefficients are identified as DC coefficients, and said DC coefficients are considered unembeddable; and further comprising selecting a threshold value, wherein coefficients having a value below said threshold value are considered small valued and thus unembeddable.

Claim 3

A method for applying a digital watermark to an image, comprising the steps of: (A) deriving from the image a plurality of component images, wherein each component image contains coefficients; (B) providing at least one look-up table containing a plurality of coefficients and corresponding values, wherein at least some of the look-up table coefficients match coefficients in said component images; and (C) embedding said watermark in said image by performing the following substeps for at least some of said component images: (1) selecting a coefficient into which a marking value, representative of a corresponding portion of the watermark, is to be embedded; (2) using the value of the selected coefficient to identify a corresponding value in said look-up table(s); (3) leaving the selected coefficient unchanged if the corresponding value is the same as the marking value; and (4) changing the selected coefficient if the corresponding value is different from the marking value; further comprising the step of identifying selected coefficients as being unembeddable, wherein said unembeddable coefficients are not employed in step (C) to embed marking values; and further comprising selecting a plurality of threshold values, wherein coefficients having values below said threshold values are considered small valued and thus unembeddable.

Claim 4

A method for applying a digital watermark to an image, comprising the steps of: (A) deriving from the image a plurality of component images, wherein each component image contains coefficients; (B) providing at least one look-up table containing a plurality of coefficients and corresponding values, wherein at least some of the look-up table coefficients match coefficients in said component images; and (C) embedding said watermark in said image by performing the following substeps for at least some of said component images: (1) selecting a coefficient into which a marking value, representative of a corresponding portion of the watermark, is to be embedded; (2) using the value of the selected coefficient to identify a corresponding value in said look-up table(s); (3) leaving the selected coefficient unchanged if the corresponding value is the same as the marking value; and (4) changing the selected coefficient if the corresponding value is different from the marking value; further comprising the step of identifying selected coefficients as being unembeddable, wherein said unembeddable coefficients are not employed in step (C) to embed marking values; and further comprising selecting a plurality of threshold values, wherein coefficients having values below said threshold values are considered small valued and thus unembeddable.

Claim 5

A method for applying a digital watermark to an image, comprising the steps of: (A) deriving from the image a plurality of component images, wherein each component image contains coefficients; (B) providing at least one look-up table containing a plurality of coefficients and corresponding values, wherein at least some of the look-up table coefficients match coefficients in said component images; (C) shuffling the coefficients prior to said embedding step; and (D) embedding said watermark in said image by performing the following substeps for at least some of said component images: (1) selecting a coefficient into which a marking value, representative of a corresponding portion of the watermark, is to be embedded; (2) using the value of the selected coefficient to identify a corresponding value in said look-up table(s); (3) leaving the selected coefficient unchanged if the corresponding value is the same as the marking value; and (4) changing the selected coefficient if the corresponding value is different from the marking value; wherein the image is divided into a plurality of component images of n×m pixels, wherein n and m are integers, and wherein each component image is transformed using the discrete cosine transform (DCT) into n×m transform coefficients; wherein the corresponding values in said look-up table(s) are binary-valued and are constrained to have a prescribed maximum run length of either binary value; wherein, in the embedding substep (D)(4), the selected coefficient is changed minimally to a value having a corresponding value in the look-up table(s) whose value is the same as the marking value, wherein the selected coefficient is changed minimally by changing its value to that of the nearest coefficient having a corresponding look-up table value equal to the marking value.

Claim 6

A method for applying a digital watermark to an image, comprising the steps of: (A) deriving from the image a plurality of component images, wherein each component image contains coefficients; (B) providing at least one look-up table containing a plurality of coefficients and corresponding values, wherein at least some of the look-up table coefficients match coefficients in said component images; (C) shuffling the coefficients prior to said embedding step; and (D) embedding said watermark in said image by performing the following substeps for at least some of said component images: (1) selecting a coefficient into which a marking value, representative of a corresponding portion of the watermark, is to be embedded; (2) using the value of the selected coefficient to identify a corresponding value in said look-up table(s); (3) leaving the selected coefficient unchanged if the corresponding value is the same as the marking value; and (4) changing the selected coefficient if the corresponding value is different from the marking value; wherein the image is divided into a plurality of component images of n×m pixels, wherein n and m are integers, and wherein each component image is transformed using the discrete cosine transform (DCT) into n×m transform coefficients; wherein the corresponding values in said look-up table(s) are binary-valued and are constrained to have a prescribed maximum run length of either binary value; wherein, in the embedding substep (D)(4), the selected coefficient is changed minimally to a value having a corresponding value in the look-up table(s) whose value is the same as the marking value, wherein the selected coefficient is changed minimally by changing its value to that of the nearest coefficient having a corresponding look-up table value equal to the marking value.

Claim 15

A method for applying a digital watermark to an image, comprising the steps of: (A) deriving from the image a plurality of component images, wherein each component image contains coefficients; (B) providing at least one look-up table containing a plurality of coefficients and corresponding values, wherein at least some of the look-up table coefficients match coefficients in said component images; (C) shuffling the coefficients; and (D) embedding said watermark in said image by performing the following substeps for at least some of said component images: (1) selecting a coefficient into which a marking value, representative of a corresponding portion of the watermark, is to be embedded; (2) using the value of the selected coefficient to identify a corresponding value in said look-up table(s); (3) leaving the selected coefficient unchanged if the corresponding value is the same as the marking value; and (4) changing the selected coefficient if the corresponding value is different from the marking value; wherein the image is divided into a plurality of component images of n×m pixels, wherein n and m are integers, and wherein each component image is transformed using the discrete cosine transform (DCT) into n×m transform coefficients; wherein the corresponding values in said look-up table(s) are binary-valued and are constrained to have a prescribed maximum run length of either binary value; wherein, in the embedding substep (C)(4), the selected coefficient is changed minimally to a value having a corresponding value in the look-up table(s) whose value is the same as the marking value, wherein the selected coefficient is changed minimally by changing its value to that of the nearest coefficient having a corresponding look-up table value equal to the marking value; and further comprising the step of identifying selected coefficients as being unembeddable, wherein said unembeddable coefficients are not employed in step (C) to embed marking values; wherein some of said coefficients are identified as DC coefficients that are considered unembeddable; and wherein coefficients having values below threshold values are considered unembeddable.

Claim 16

A method for applying a digital watermark to an image, comprising the steps of: (A) deriving from the image a plurality of component images, wherein each component image contains coefficients; (B) providing at least one look-up table containing a plurality of coefficients and corresponding values, wherein at least some of the look-up table coefficients match coefficients in said component images; (C) shuffling the coefficients; and (D) embedding said watermark in said image by performing the following substeps for at least some of said component images: (1) selecting a coefficient into which a marking value, representative of a corresponding portion of the watermark, is to be embedded; (2) using the value of the selected coefficient to identify a corresponding value in said look-up table(s); (3) leaving the selected coefficient unchanged if the corresponding value is the same as the marking value; and (4) changing the selected coefficient if the corresponding value is different from the marking value; wherein the image is divided into a plurality of component images of n×m pixels, wherein n and m are integers, and wherein each component image is transformed using the discrete cosine transform (DCT) into n×m transform coefficients; wherein the corresponding values in said look-up table(s) are binary-valued and are constrained to have a prescribed maximum run length of either binary value; wherein, in the embedding substep (C)(4), the selected coefficient is changed minimally to a value having a corresponding value in the look-up table(s) whose value is the same as the marking value, wherein the selected coefficient is changed minimally by changing its value to that of the nearest coefficient having a corresponding look-up table value equal to the marking value; and further comprising the step of identifying selected coefficients as being unembeddable, wherein said unembeddable coefficients are not employed in step (C) to embed marking values; wherein some of said coefficients are identified as DC coefficients that are considered unembeddable; and wherein coefficients having values below threshold values are considered unembeddable.

Claim 17

A method for applying a digital watermark to an image, comprising the steps of: (A) deriving from the image a plurality of component images, wherein each component image contains coefficients; (B) providing at least one look-up table containing a plurality of coefficients and corresponding values, wherein at least some of the look-up table coefficients match coefficients in said component images; (C) shuffling the coefficients prior to said embedding step; and (D) embedding said watermark in said image by performing the following substeps for at least some of said component images: (1) selecting a coefficient into which a marking value, representative of a corresponding portion of the watermark, is to be embedded; (2) using the value of the selected coefficient to identify a corresponding value in said look-up table(s); (3) leaving the selected coefficient unchanged if the corresponding value is the same as the marking value; and (4) changing the selected coefficient if the corresponding value is different from the marking value. wherein the image is divided into a plurality of component images of size n×m pixels, wherein n and m are integers, and wherein each component image is transformed into coefficients; further comprising the step of shuffling the coefficients prior to said embedding step; wherein said shuffling step comprises concatenating the coefficients of a plurality of component images into a string and shuffling the order of the coefficients in said string; and wherein the shuffled string of coefficients are put into a plurality of sub-strings and each sub-string is used to embed one watermark or is to be used for error detection or for error correction.

Claim 18

A method for applying a digital watermark to an image, comprising the steps of: (A) deriving from the image a plurality of component images, wherein each component image contains coefficients; (B) providing at least one look-up table containing a plurality of coefficients and corresponding values, wherein at least some of the look-up table coefficients match coefficients in said component images; (C) shuffling the coefficients prior to said embedding step; and (D) embedding said watermark in said image by performing the following substeps for at least some of said component images: (1) selecting a coefficient into which a marking value, representative of a corresponding portion of the watermark, is to be embedded; (2) using the value of the selected coefficient to identify a corresponding value in said look-up table(s); (3) leaving the selected coefficient unchanged if the corresponding value is the same as the marking value; and (4) changing the selected coefficient if the corresponding value is different from the marking value. wherein the image is divided into a plurality of component images of size n×m pixels, wherein n and m are integers, and wherein each component image is transformed into coefficients; further comprising the step of shuffling the coefficients prior to said embedding step; wherein said shuffling step comprises concatenating the coefficients of a plurality of component images into a string and shuffling the order of the coefficients in said string; and wherein the shuffled string of coefficients are put into a plurality of sub-strings and each sub-string is used to embed one watermark or is to be used for error detection or for error correction.

Claim 19

A method for applying a digital watermark to an image, comprising the steps of: (A) deriving from the image a plurality of component images, wherein each component image contains coefficients; (B) providing at least one look-up table containing a plurality of coefficients and corresponding values, wherein at least some of the look-up table coefficients match coefficients in said component images; (C) shuffling the coefficients prior to said embedding step; and (D) embedding said watermark in said image by performing the following substeps for at least some of said component images: (1) selecting a coefficient into which a marking value, representative of a corresponding portion of the watermark, is to be embedded; (2) using the value of the selected coefficient to identify a corresponding value in said look-up table(s); (3) leaving the selected coefficient unchanged if the corresponding value is the same as the marking value; and (4) changing the selected coefficient if the corresponding value is different from the marking value. wherein the image is divided into a plurality of component images of size n×m pixels, wherein n and m are integers, and wherein each component image is transformed into coefficients; further comprising the step of shuffling the coefficients prior to said embedding step; wherein said shuffling step comprises concatenating the coefficients of a plurality of component images into a string and shuffling the order of the coefficients in said string; and wherein the shuffled string of coefficients are put into a plurality of sub-strings and each sub-string is used to embed one watermark or is to be used for error detection or for error correction.

Claim 20

A method for applying a digital watermark to an image, comprising the steps of: (A) deriving from the image a plurality of component images, wherein each component image contains coefficients; (B) providing at least one look-up table containing a plurality of coefficients and corresponding values, wherein at least some of the look-up table coefficients match coefficients in said component images; (C) shuffling the coefficients prior to said embedding step; and (D) embedding said watermark in said image by performing the following substeps for at least some of said component images: (1) selecting a coefficient into which a marking value, representative of a corresponding portion of the watermark, is to be embedded; (2) using the value of the selected coefficient to identify a corresponding value in said look-up table(s); (3) leaving the selected coefficient unchanged if the corresponding value is the same as the marking value; and (4) changing the selected coefficient if the corresponding value is different from the marking value. wherein the image is divided into a plurality of component images of size n×m pixels, wherein n and m are integers, and wherein each component image is transformed into coefficients; further comprising the step of shuffling the coefficients prior to said embedding step; wherein said shuffling step comprises concatenating the coefficients of a plurality of component images into a string and shuffling the order of the coefficients in said string; and wherein the shuffled string of coefficients are put into a plurality of sub-strings and each sub-string is used to embed one watermark or is to be used for error detection or for error correction.