Curved wavelet transform for image and video compression
First Claim
1. A method of image transformation comprising:
- transforming an n-dimensional image, wherein n≧
2, into a wavelet-transformed image comprised of wavelet coefficients by performing one-dimensional wavelet transformations on image values along a plurality of curved paths dependent upon content of the image, using the steps of;
a) determining the plurality of curved paths within the image;
b) determining image values along each of the curved paths;
d) performing the one-dimensional wavelet transformations on the image values along the curved paths using a low-pass 1-D wavelet filter and a high-pass 1-D wavelet filter along each of the curved paths to obtain a low-pass filtered image comprised of low-pass wavelet coefficients and a high-pass filtered image comprised of high-pass wavelet coefficients; and
,e) down-sampling the low-pass and the high-pass filtered images along the first coordinate to obtain down-sampled low-pass and high-pass filtered images.
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Abstract
A curved wavelet transform and a related image/video compression system are disclosed. The curved wavelet transform (CWT) is carried out by applying one-dimensional (1-D) wavelet filters along curves, rather than along only horizontal and vertical directions. The image/video compression system includes a curve determination unit, a curved wavelet transform unit, a wavelet coefficient quantization unit, a wavelet coefficient coding unit, and a curve coding unit. The quantization and coding of the wavelet coefficients are related to the curves. In one embodiment, recursive wavelet filters are used for inverse wavelet decomposition. The system provides higher compression capability than conventional wavelet-based image compression systems.
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Citations
21 Claims
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1. A method of image transformation comprising:
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transforming an n-dimensional image, wherein n≧
2, into a wavelet-transformed image comprised of wavelet coefficients by performing one-dimensional wavelet transformations on image values along a plurality of curved paths dependent upon content of the image, using the steps of;a) determining the plurality of curved paths within the image; b) determining image values along each of the curved paths; d) performing the one-dimensional wavelet transformations on the image values along the curved paths using a low-pass 1-D wavelet filter and a high-pass 1-D wavelet filter along each of the curved paths to obtain a low-pass filtered image comprised of low-pass wavelet coefficients and a high-pass filtered image comprised of high-pass wavelet coefficients; and
,e) down-sampling the low-pass and the high-pass filtered images along the first coordinate to obtain down-sampled low-pass and high-pass filtered images. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 18, 19, 20, 21)
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16. An image encoding system for encoding and compressing images into encoded image data, the images represented using arrays of pixels, the image encoding system comprising:
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a curve determination unit for determining a plurality of curved paths in an image wherein substantially each pixel is associated with a curved path from the plurality of curved paths; a curved wavelet transform unit for performing wavelet transformations of image values along the plurality of curved paths and for outputting wavelet transformed images represented by wavelet coefficients; a curve coding unit for coding the plurality of curved paths; a wavelet coefficient quantization unit for performing curved path adaptive quantization of the wavelet coefficients; and
,a wavelet coefficient coding unit for performing curved path adaptive coding of the wavelet coefficients. - View Dependent Claims (17)
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Specification