A system and method of a forward and/or inverse discrete cosine transform in a video system. In one embodiment, an array of DCT transform coefficients are converted to a two dimensional array of spatial data. The array of DCT transform coefficients are first operated upon by a pre-scale computati...
Inventor: Alex Z. Mou Assignees: Sun Microsystems, Inc. Primary Examiner: David H. Malzahn Attorneys: Meyertons Hood Kivlin Kowert & Goetzel, P.C., B. Nel Kivlin U.S. Classification
708/402; 382/250 International Classification
G06F 1714 View patent at USPTO |
Citations|
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ClaimsWhat is claimed is: 1. A method for performing a forward discrete cosine transform (DCT) upon a matrix of image data in a video system, the method comprising: - performing a column-wise calculation upon each column of said matrix of image data to obtain an intermediary array;
- performing a row-wise calculation upon each row of said intermediary array to obtain an unscaled DCT array; and
- multiplying said unscaled DCT array element-wise with corresponding elements of a symmetric post-scale factor array to produce an output DCT array which represents the image data in a frequency domain;
- wherein said symmetric post-scale factor array is an array expressible by the product MUM, wherein U is a matrix of coefficients each being equal to 1, wherein M is an array having a set of post-scale constants along a diagonal and all zeros off the diagonal, wherein said set of post-scale constants are taken from the collection of values defined by cos(n/16), where n1, 2, 3, 4.
2. The method for performing a forward discrete cosine transform as recited in claim 1 further comprising retrieving each element of said matrix of data from a memory. 3. A method for performing a forward discrete cosine transform (DCT) upon a matrix of image data in a video system, the method comprising: - performing a row-wise calculation upon each row of said matrix of image data to obtain an intermediary array;
- performing a column-wise calculation upon each column of said intermediary array to obtain an unscaled DCT array; and
- multiplying said unscaled DCT array element-wise with corresponding elements of a symmetric post-scale factor array to produce an output DCT array which represents the image data in a frequency domain;
- wherein said symmetric post-scale factor array is an array expressible by the product MUM, wherein U is a matrix of coefficients each being equal to 1, wherein M is an array having a set of post-scale constants along a diagonal and all zeros off the diagonal, wherein said set of post-scale constants are taken from the collection of values defined by cos(n/16), where n1, 2, 3, 4.
4. The method for performing a forward discrete cosine transform as recited in claim 3 further comprising retrieving each element of said matrix of data from a memory. 5. A discrete cosine transform calculation unit for a video system, configured to perform a discrete cosine transform (DCT) upon a matrix of image data, said discrete cosine transform calculation unit comprising: - a column vector computation unit configured to perform a column-wise calculation upon each column of said matrix of image data to obtain an intermediary array;
- a row vector computation unit configured to perform a row-wise calculation upon each row of said intermediary array to obtain an unscaled DCT array; and
- a postscale computation unit configured to multiply said unscaled DCT array element-wise with corresponding elements of a symmetric post-scale factor array to produce an output DCT array which represents the image data in a frequency domain;
- wherein said symmetric post-scale factor array is an array expressible by the product MUM, wherein U is a matrix of coefficients each being equal to 1, wherein M is an array having a set of post-scale constants along a diagonal and all zeros off the diagonal, wherein said set of post-scale constants are taken from the collection of values defined by cos(n/16), where n1, 2, 3, 4.
6. A discrete cosine transform calculation unit for a video system, configured to perform a discrete cosine transform (DCT) upon a matrix of image data, said discrete cosine transform calculation unit comprising: - a row vector computation unit configured to perform a row-wise calculation upon each row of said matrix of image data to obtain an intermediary array;
- a column vector computation unit configured to perform a column-wise calculation upon each column of said intermediary array to obtain an unscaled DCT array; and
- a postscale computation unit configured to multiply said unscaled DCT array element-wise with corresponding elements of a symmetric post-scale factor array to produce an output DCT array which represents the image data in a frequency domain;
- wherein said symmetric post-scale factor array is an array expressible by the product MUM, wherein U is a matrix of coefficients each being equal to 1, wherein M is an array having a set of post-scale constants along a diagonal and all zeros off the diagonal, wherein said set of post-scale constants are taken from the collection of values defined by cos(n/16), where n1, 2, 3, 4.
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