Abstract: A method is disclosed of encoding data including transforming the data into a series of components having different frequency characteristics, said components each including a series of coefficients; encoding said coefficients in a compact form, said coefficients including a binary string and said encoding including providing a first efficient encoding technique to encode the number of leading zeros in said binary string, and rounding said coefficients such that a rounded coefficient does not alter significantly the efficient coding of the leading zeros. Preferably, the rounding can includes discarding a first number of insignificant coefficients and adding one to the more significant coefficients only where the more significant coefficients are not zero. The invention has particular application when utilized in encoding wavelet transformed data and when utilized on image data.

Abstract: A method of providing a thumbnail-size colour digital image in a bit stream of a larger size colour digital image is disclosed. The bit stream of the larger digital image is typically in a compressed format, and includes a thumbnail size image in a substantially uncompressed format. The method includes converting input colour values of the larger colour image from a first colour format to corresponding values in a Luminance, Chrominance-blue, Chrominance-red (Y,Cb,Cr) colour format, A transform is then applied to said corresponding values to decompose the larger digital image into a DC subband and one or more higher frequency subbands. Typically the transform is a discrete wavelet transform. The DC subband is then output to the bit stream in an uncompressed format. Then at least one of the one or more higher frequency subbands is encoded into the bit stream in a substantially compressed format. The DC subband thus represents a thumbnail-size colour digital image in the bit stream.

Abstract: A method of producing a transform decomposition of data having an odd length the method comprising the steps of dividing the data into a portion having an even length of one element; performing a discrete wavelet transform on the even length data to produce low frequency subband data and high frequency subband data; adding the difference of the one element and an adjacent element to high frequency subband data. Preferably the transform is a Discrete Wavelet Transform utilised in the compression of image data.

Abstract: Methods, apparatus and computer program products for encoding and decoding transform coefficients are disclosed. A digital image (102) is input to a transform block (110), which preferably employs a discrete wavelet transform. A bit rearrangement block (120) codes bit sequences representing resulting transform coefficients (112) in an efficient fashion. The bit arrangement block (120) selects a portion of the coefficients as a region (200). The significance of each bitplane of the region (200) is scanned from most towards least significant bitplanes, and first and second tokens are provided for each insignificant and significant bitplanes until determining a significant bitplane. This region is then partitioned into subregions (210-216), which are each set as the selected region. This processing is repeated until a minimum bit level is reached, or the selected region has a specified size. The coefficients of specified-size regions (200-216) are coded and provided in a coded representation (122).