| US 7,539,354 B2 | ||
| Image database key generation method | ||
| Stephen James Hardy, West Pymble (Australia); Peter Alleine Fletcher, Rozelle (Australia); Kieran Gerard Larkin, Putney (Australia); and Ian Richard Gibson, Coogee (Australia) | ||
| Assigned to Canon Kabushiki Kaisha, Tokyo (Japan) | ||
| Filed on Aug. 03, 2005, as Appl. No. 11/195,644. | ||
| Claims priority of application No. 2004904856 (AU), filed on Aug. 25, 2004. | ||
| Prior Publication US 2006/0050985 A1, Mar. 09, 2006 | ||
| Int. Cl. G06K 9/36 (2006.01) | ||
| U.S. Cl. 382—276 [382/295; 382/280; 713/176] | 16 Claims |
| 1. A method of generating a matching key for an image with said matching key being substantially invariant to rotation, scale
and translation, said method comprising the steps of:
forming a spatial domain representation of said image that is substantially invariant to translation of said image;
transforming at least one of rotation and scaling of said image in said spatial domain representation into translation to
form a transformed image; and
forming a spatial domain representation of said transformed image that is substantially invariant to translation of said transformed
image, said spatial domain representation of said transformed image being said matching key from said image,
wherein the step of forming said spatial domain representation of said image comprises the sub-steps of:
performing a Fourier transform of said image to form a Fourier transformed image;
performing a function on the magnitude component of said Fourier transformed image to form an altered Fourier transformed
image, said function being commutative within a constant to rotation and scale; and
performing an inverse Fourier transform on said altered Fourier transformed image to form said spatial domain representation.
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