Image transformations in the compressed domain

Claim 3

The method as recited in claim 1 , wherein the step of transposing the sequence of non-zero elements within each of the data blocks further comprises the steps of: sequentially examining the sequence of non-zero elements of each of the plurality of data blocks; determining the non-zero elements that are positioned within a same one of a plurality of cross-diagonals of each data block; and reversing the order of non-zero elements positioned within the same cross-diagonal.

Claim 4

The method as recited in claim 1 , wherein the dihedral symmetry operation comprises flipping the digital image over its main diagonal.

Claim 5

The method as recited in claim 1 , further comprising the step of applying sign-changes to the sequence of non-zero elements within each data block wherein the dihedral symmetry operation comprises flipping the digital image over its main cross-diagonal axis.

Claim 6

The method as recited in claim 1 , further comprising the step of applying sign-changes to the sequence of non-zero elements within each data block wherein the dihedral symmetry operation comprises rotating the digital image 90° clockwise.

Claim 7

The method as recited in claim 1 , further comprising the step of applying sign-changes to the sequence of non-zero elements within each data block wherein the dihedral symmetry operation comprises rotating the digital image 90° counterclockwise.

Claim 8

The method as recited in claim 4 , wherein, after transposing the sequence of non-zero elements within each data block, sign-reversing every other non-zero element within each data block without expanding into a full data block.

Claim 9

The method as recited in claim 5 , wherein, after transposing the sequence of non-zero elements within each data block, sign-reversing the odd-column non-zero elements within each data block without expanding into a full data block.

Claim 10

The method as recited in claim 6 , wherein, after transposing the sequence of non-zero elements within each data block, sign-reversing the odd-row non-zero elements within each data block without expanding into a full data block.

Claim 11

A digital camera, comprising: a sensor for capturing light and converting the light into an analog image signal; an analog-to-digital converter for converting the analog image signal to a digital image in spatial domain; and a digital image processor for compressing the digital image from a spatial domain representation of the digital image to a linear transform domain representation of the digital image defined by a plurality of linear-transform-based coded data blocks, wherein elements of the data blocks are coded as a sequence of symbol trios during the compressing, wherein said digital image processor parses compressed image data of the digital image to extract an offset value and a DC value for each of the plurality of linear-transform-based coded data blocks, accesses each of the plurality of linear-transform-based coded data blocks by using the corresponding offset value, extracts a sequence of non-zero elements of each of the plurality of linear-transform-based coded data blocks, transposes the sequence of non-zero elements within each data block without expanding into a full data block, applies sign change to non-zero elements within each data block and codes the sequence of non-zero elements of each data block, without de-zigzagging and zigzagging the elements of each data block, to perform a dihedral symmetry operation on the spatial domain representation of the digital image.

Claim 12

A digital camera, comprising: a sensor for capturing light and converting the light into an analog image signal; an analog-to-digital converter for converting the analog image signal to a digital image in spatial domain; and a digital image processor for compressing the digital image from a spatial domain representation of the digital image to a linear transform domain representation of the digital image defined by a plurality of linear-transform-based coded data blocks, wherein elements of the data blocks are coded as a sequence of symbol trios during the compressing, wherein said digital image processor parses compressed image data of the digital image to extract an offset value and a DC value for each of the plurality of linear-transform-based coded data blocks, accesses each of the plurality of linear-transform-based coded data blocks by using the corresponding offset value, extracts a sequence of non-zero elements of each of the plurality of linear-transform-based coded data blocks, transposes the sequence of non-zero elements within each data block without expanding into a full data block, applies sign change to non-zero elements within each data block and codes the sequence of non-zero elements of each data block, without de-zigzagging and zigzagging the elements of each data block, to perform a dihedral symmetry operation on the spatial domain representation of the digital image.

Claim 13

The digital camera as recited in claim 10 , wherein the dihedral symmetry operation comprises rotating the digital image 90° clockwise.

Claim 14

The digital camera as recited in claim 10 , wherein the dihedral symmetry operation comprises flipping the digital image over its main cross diagonal.

Claim 15

The digital camera as recited in claim 10 , wherein the dihedral symmetry operation comprises rotating the digital image 90° counterclockwise.

Claim 16

The digital camera as recited in claim 11 , wherein, after said digital image processor transposes the sequence of non-zero elements within each data block, said digital image processor sign-reverses the odd-column non-zero elements within each data block without expanding into a full data block.

Claim 17

The digital camera as recited in claim 12 , wherein, after said digital image processor transposes the sequence of non-zero elements within each data block, said digital image processor sign-reverses every other non-zero element within each data block without expanding into a full data block.

Claim 18

The digital camera as recited in claim 13 , wherein, after said digital image processor transposes the sequence of non-zero elements within each data block, said digital image processor sign-reverses the odd-row non-zero elements within each data block without expanding into a full data block.

Claim 19

A computer system having a computer-readable program code embodied therein for causing the computer system to geometrically transform a digital image in spatial domain by performing the steps of: processing the digital image to obtain a linear transform domain representation of the digital image defined by a plurality of linear-transform-based coded data blocks, wherein elements of the data blocks are coded as a sequence of symbol trios so that the steps are performed without de-zigzagging and zigzagging the elements of each data block; parsing the compressed image data to extract an offset value and a DC value for each of the plurality of linear-transform-based coded data blocks; accessing each of the plurality of linear-transform-based coded data blocks by using the corresponding offset value; extracting a sequence of non-zero elements from each of the plurality of linear-transform-based coded data blocks; transposing the sequence of non-zero elements within each data block without expanding into a full data block; and coding the transposed sequence of non-zero elements of each data block; wherein the spatial domain representation of the digital image undergoes a dihedral symmetry operation.

Claim 20

A computer system having a computer-readable program code embodied therein for causing the computer system to geometrically transform a digital image in spatial domain by performing the steps of: processing the digital image to obtain a linear transform domain representation of the digital image defined by a plurality of linear-transform-based coded data blocks, wherein elements of the data blocks are coded as a sequence of symbol trios so that the steps are performed without de-zigzagging and zigzagging the elements of each data block; parsing the compressed image data to extract an offset value and a DC value for each of the plurality of linear-transform-based coded data blocks; accessing each of the plurality of linear-transform-based coded data blocks by using the corresponding offset value; extracting a sequence of non-zero elements from each of the plurality of linear-transform-based coded data blocks; transposing the sequence of non-zero elements within each data block without expanding into a full data block; and coding the transposed sequence of non-zero elements of each data block; wherein the spatial domain representation of the digital image undergoes a dihedral symmetry operation.

Claim 21

The computer system as recited in claim 17 , wherein the step of transposing the sequence of non-zero elements within each of the data blocks further comprises the steps of: sequentially examining the sequence of non-zero elements of each of the plurality of data blocks; determining the non-zero elements that are positioned within a same one of a plurality of cross-diagonals of each data block; and reversing the order of non-zero elements positioned within the same cross-diagonal.

Claim 22

The computer system as recited in claim 17 , wherein the dihedral symmetry operation comprises flipping the digital image over its main diagonal.

Claim 23

The computer system as recited in claim 17 , further comprising the step of applying a sign change to non-zero elements wherein the dihedral symmetry operation comprises rotating the digital image over its main cross-diagonal axis.

Claim 24

The computer system as recited in claim 17 , further comprising the step of applying a sign change to non-zero elements wherein the dihedral symmetry operation comprises rotating the digital image 90° clockwise.

Claim 25

The computer system as recited in claim 17 , further comprising the step of applying a sign change to non-zero elements wherein the dihedral symmetry operation comprises rotating the digital image 90° counterclockwise.

Claim 26

The computer system as recited in claim 20 , wherein, after transposing the sequence of non-zero elements within each data block, sign-reversing every other non-zero element within each data block without expanding into a full data block.

Claim 27

The computer system as recited in claim 21 , wherein, after transposing the sequence of non-zero elements within each data block, sign-reversing the odd-column non-zero elements within each data block without expanding into a full data block.

Claim 28

The computer system as recited in claim 22 , wherein, after transposing the sequence of non-zero elements within each data block, sign-reversing the odd-row non-zero elements within each data block without expanding into a full data block.

Claim 31

The method as recited in claim 26 , wherein the dihedral symmetry operation comprises rotating the digital image over its middle-horizontal axis.

Claim 32

The method as recited in claim 26 , wherein the dihedral symmetry operation comprises rotating the digital image over its middle-vertical axis.

Claim 33

The method as recited in claim 26 , wherein the dihedral symmetry operation comprises rotating the digital image 180°.

Claim 34

The method as recited in claim 27 , wherein the step of applying sign-changes is applied to sign-reverse the odd-column elements within each data block without expanding into a full data block.

Claim 35

The method as recited in claim 28 , wherein the step of applying sign-changes is applied to sign-reverse the odd-row elements within each data block without expanding into a full data block.

Claim 36

The method as recited in claim 29 , wherein the step of applying sign-changes is applied to sign-reverse every other element within each data block without expanding into a full data block.

Claim 37

The method as recited in claim 1 , wherein the symbol trio comprises first, second and third symbols, the first symbol representing the number of consecutive zeros in a zigzag ordering of the corresponding data block, and the next non-zero element has a value x such that: S=┌log 2 (|x|+1)┐, V = S   least    significant    bits    of   { x when   x > 0 x - 1 when   x < 0.  wherein S represents the second symbol and V represents the third symbol.

Claim 38

The digital camera as recited in claim 10 , wherein the symbol trio comprises first, second and third symbols, the first symbol representing the number of consecutive zeros in a zigzag ordering of the corresponding data block, and the next non-zero element has a value x such that: S=┌log 2 (|x|+1)┐, V = S   least    significant    bits    of   { x when   x > 0 x - 1 when   x < 0.  wherein S represents the second symbol and V represents the third symbol.

Claim 39

The computer system as recited in claim 17 , wherein the symbol trio comprises first, second and third symbols, the first symbol representing the number of consecutive zeros in a zigzag ordering of the corresponding data block, and the next non-zero element has a value x such that: S=┌log 2 (|x|+1), V = S   least    significant    bits    of   { x when   x > 0 x - 1 when   x < 0.  wherein S represents the second symbol and V represents the third symbol.

Claim 40

The method as recited in claim 26 , wherein the symbol trio comprises first, second and third symbols, the first symbol representing the number of consecutive zeros in a zigzag ordering of the corresponding data block, and the next non-zero element has a value x such that: S=┌log 2 (|x|+1), V = S   least    significant    bits    of   { x when   x > 0 x - 1 when   x < 0.  wherein S represents the second symbol and V represents the third symbol.