Scaled forward and inverse discrete cosine transform and video c

Details Scaled forward and inverse discrete cosine transform and video c Scaled forward and inverse discrete cosine transform and video c

1997-06-13

2000-10-17

Kelley, Chris S.

Pulse or digital communications

Bandwidth reduction or expansion

Television or motion video signal

348403, 364725, 382232, H01N 712, H04B 166

Patent

active

06134270&

ABSTRACT:
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 computation unit (implemented in either hardware or software) which multiplies a set of predetermined pre-scale constants with the input coefficients. The pre-scale constants multiplied by the input DCT coefficient matrix form a symmetric pre-scale array. Upon pre-scaling using the symmetric pre-scale factor array, an intermediary array is composed by performing intermediary calculations upon each column vector of the pre-scaled array. The output of this intermediary calculation is composed to form an intermediary array. Subsequently, a set of calculations are performed row-wise upon each row vector of the intermediary array to thereby form the output array of spatial data. In one implementation, the array of pre-scale coefficients (i.e., the symetric pre-scale factor array) may be represented as the result of a matrix multiplication M.times.U.times.M, where the array U consists of a set of coefficients all equal to 1, and wherein the array M is an array of coefficients wherein the equal row-column diagonal of coefficients include a set of pre-scale constants and all other coefficients in the array are equal to 0. The pre-scale constants includes a set of constants expressed by the cos(.pi./16), where n=1, 2, 3 and 4. In another embodiment, the calculations are reversed to perform a forward discrete cosine transform operation.

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