Canon Kabushiki Kaisha

Paul Raymond Higginbottom

James Philip Andrew

Eric Majani

Patrice Onno

Yu-Ling Chen

Bertrand Berthelot

Julie Yan Zhu

A method of encoding an digital image () by a discrete wavelet transform (DWT) to a predetermined level of decomposition on a block by block basis, each block () having a specified size in number of coefficients, is disclosed. The image is divided into tiles, each having dimensions required to produce the number of coefficients in a first dimension of the transformed block at the predetermined level of decomposition, and less than the number of coefficients in a second dimension of the transformed block. At a particular DWT level, tiles are decomposed. HH, HL and LH subband coefficients are accumulated to form blocks of specified size, and these are encoded to a bit stream (). A predetermined number of associated LL subband coefficients are similarly accumulated, the process performed recursively per DWT level until the predetermined decomposition level is attained, and the corresponding LL subband coefficients encoded to the bit stream ().

Encoding method and apparatus

Disclosed is a method of detecting a predetermined mark embedded in an image. The mark () comprises a predetermined arrangement of a plurality of elements (), each element having a predetermined colour characteristic and predetermined shape. The method processes () the image to provide an encoded representation of the image at a predetermined resolution (eg. 200 dpi). The coordinate positions for substantially each of the elements of the mark embedded in the image are detected (), wherein the detection is characterised by applying at least one mask () to substantially each pixel of the encoded representation. From the coordinate positions, a set of spatial features representing a spatial arrangement of the detected elements are then determined (). The determined set of spatial features is then compared () to a known set of spatial features to provide a confidence level measure for a degree of matching between the known set and the determined set of spatial features.

Method and apparatus for mark detection

A digital signal is transformed in at least two different frequency bands according to at least two different resolutions. The signal is divided into first blocks all having the same predetermined first number of samples. Each of the first blocks is transformed into a plurality of second blocks, any second block under consideration having a second respective number of samples which depends on the resolution of the second block under consideration, and containing samples selected according to their frequency. Second blocks issuing from the transformation of different first blocks are grouped in order to form third blocks all having the same predetermined third number of samples which is at least equal to the largest of the second numbers.

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Castle Hill, Australia

Paul Raymond Higginbottom