Data processing apparatus and method of processing data

A method of processing data representative of an image to modify said image so that a subsequent non-linear distortion applied to said image may be determined, said method comprising combining at least first and second template signals into different first and second frequency bands respectively of a data signal representative of an image, said first template signal and said second template signal being copies of the same reference signal and are combined in said first and second bands with the effect that distortion of said data signal produces a detectable relative change in frequency between said first and said second template signals.

A data processing apparatus operable to modify data representative of an image so that a subsequent non-linear distortion applied to said image may be determined, said apparatus comprising:

• (a) means for combining at least first and second template signals into first and second frequency bands respectively of a data signal representative of an image, said first template signal and said second template signal being copies of the same reference signal;
• and
• (b) means for combining said first and second bands with the effect that distortion of said data signal produces a detectable relative change in frequency between said first and said second template signals.

A data processing apparatus operable to determine non-linear distortion applied to an image in which template signals have been introduced into at least first and second frequency bands of said image respectively by a data processing apparatus operable to combine at least first and second template signals into said first and second frequency bands, said template signals having a predetermined relationship with each other and being combined in said first and second bands with the effect that distortion of said data signal produces a detectable relative change in frequency between said first and said second template signals, said apparatus comprising

• a transform detection processor operable to generate at least one parameter representative of a linear transformation applied to each of selected parts of said image, and
• a non-linear transform processor operable to estimate parameters of a non-linear transformation representative of said non-linear distortion applied to said image from the linear transform parameters of at least two parts of said image.

A method of processing data representative of an image to determine non-linear distortion applied to the image in which template signals have been introduced into at least first and second frequency bands of said image respectively by combining at least first and second template signals into said first and second frequency bands, said template signals having a predetermined relationship with each other and being combined in said first and second bands with the effect that distortion of said data signal produces a detectable relative change in frequency between said first and said second template signals, said method comprising:

• (a) generating data representative of selected parts of said image,
• (b) generating at least one parameter representative of a linear transformation applied to each of said parts of said image, and
• (c) estimating parameters of a non-linear transformation representative of said non-linear distortion applied to said image from the linear transform parameters of at least two parts of said image.

A data processing apparatus operable to determine non-linear distortion applied to an image in which template signals have been introduced into at least first and second frequency bands of said image respectively by a data processing apparatus operable to combine at least first and second template signals into said first and second frequency bands, said first template signal and said second template signal being copies of the same reference signal and being combined in said first and second bands with the effect that distortion of said data signal produces a detectable relative change in frequency between said first and said second template signals, said apparatus comprising:

• a transform detection processor operable to generate at least one parameter representative of a linear transformation applied to each of selected parts of said image;
• and
• a non-linear transform processor operable to estimate parameters of a non-linear transformation representative of said non-linear distortion applied to said image from the linear transform parameters of at least two parts of said image.