Lines Matching defs:idct
24 inverse discrete cosine transform (IDCT).
32 #include "idct.h"
38 FUNCTION NAME: idct
40 INPUT AND OUTPUT DEFINITIONS FOR idct
57 blk points to the found IDCT values for an 8r8 image block.
66 FUNCTION DESCRIPTION FOR idct
70 dimensional inverse discrete cosine transform (IDCT).
80 2-D IDCT can be separated as horizontal(row-wise) and vertical(column-wise)
81 1-D IDCTs. Therefore, 2-D IDCT values are found by the following two steps:
82 1. Find horizontal 1-D IDCT values for each row from 8r8 dequantized DCT
83 coefficients by row IDCT operation.
90 2. Find vertical 1-D IDCT values for each column from the results of 1
91 by column IDCT operation.
99 REQUIREMENTS FOR idct
105 /* REFERENCES FOR idct */
106 /* idct.c, inverse fast discrete cosine transform
119 ; Function Code FOR idct
140 /* column (vertical) IDCT */
146 /* since row IDCT results have net left shift by 3 */
164 /* make output of IDCT >>3 or scaled by 1/8 and */
213 /* net shift of IDCT is >>3 after the following */
214 /* shift operation, it makes output of 2-D IDCT */
216 /* 1/(2*sqrt(2)) for row IDCT and column IDCT. */
228 /* row (horizontal) IDCT */
252 /* output of row IDCT scaled by 8 */
306 /* row IDCT scaled by 8 to retain 3 bits precision*/
344 void idct(
363 /* column (vertical) IDCT */
369 /* since row IDCT results have net left shift by 3 */
387 /* make output of IDCT >>3 or scaled by 1/8 and */
436 /* net shift of IDCT is >>3 after the following */
437 /* shift operation, it makes output of 2-D IDCT */
439 /* 1/(2*sqrt(2)) for row IDCT and column IDCT. */
451 /* row (horizontal) IDCT */
475 /* output of row IDCT scaled by 8 */
527 /* row IDCT scaled by 8 to retain 3 bits precision*/
577 ; End Function: idct
