Defining image features and using features to monitor image transformations
AssigneeSnell Limited
InventorMichael James Knee
Life of this patent
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Abstract
For monitoring an image transformation such as aspect ratio conversion, an image feature is defined by identifying a position in the image having a local spatial maximum value and then identifying four other positions in the image having local spatial minimum values such that the four minimum value positions surround the position of the maximum, a first pair of the minimums lie on a first line passing through maximum and a second pair of the minimums lie on a second line passing through the maximum.
Claims17
A method of monitoring in a processor a transformation between a first image and a second image, comprising the steps of identifying at least one image feature in the first image and at least one image feature in the second image by, for each image, identifying a first position in the image having a local spatial extremum value of an image parameter of the said image;
- identifying at least two other positions in the image having local spatial extremum values of the said image parameter such that no straight line passes through the first position and both said other positions;
- and storing or outputting data defining said first position and said other positions at least relative to said first position.
Image processing apparatus comprising a local maximum finder for identifying a first position in the image having a local spatial maximum value of an image parameter of the said image;
- and a minimum finder for identifying four other positions in the image having local spatial minimum values of the said image parameter such that
- the said four minimum value positions surround the position of the said local spatial maximum value, and
- a first pair of the said minimum value positions lie on a first line passing through the position of the said local spatial maximum and a second pair of the said minimum value positions lie on a second line passing through the position of the said local spatial maximum.
Image processing apparatus comprising an upstream feature detector for identifying at least N image features in a first image by identifying a first position in the first image having a local spatial extremum value of an image parameter of the said image;
- identifying at least two other positions in the first image having local spatial extremum values of the said image parameter such that no straight line passes through the first position and both said other positions;
- a downstream feature detector for identifying at least M image features in a second image by identifying a first position in the second image having a local spatial extremum value of an image parameter of the second image;
- identifying at least two other positions in the second image having local spatial extremum values of the said image parameter such that no straight line passes through the first position and both said other positions;
- a corresponding feature selector for selecting at least two detected image features in the second image which correspond respectively with detected image features in the first image and a transform coefficient unit for computing from the location of the selected and corresponding image features coefficients of a transform between the first image and the second image.
Dependencies are inferred from the claim text.