Performs dequantization, inverse DCT and level shift of an 8x8 block with zero high frequency components.
IppStatus ippiDCTQuantInv8x8LS_4x4_JPEG_16s8u_C1R(const Ipp16s* pSrc, Ipp8u* pDst, int dstStep, const Ipp16u* pQuantInvTable);
IppStatus ippiDCTQuantInv8x8LS_2x2_JPEG_16s8u_C1R(const Ipp16s* pSrc, Ipp8u* pDst, int dstStep, const Ipp16u* pQuantInvTable);
IppStatus ippiDCTQuantInv8x8LS_1x1_JPEG_16s8u_C1R(const Ipp16s* pSrc, Ipp8u* pDst, int dstStep, const Ipp16u* pQuantInvTable);
pSrc |
Pointer to the 8x8 block of quantized DCT coefficients. |
pDst |
Pointer to the 8x8 block in the destination image. |
dstStep |
Distance in bytes between starts of consecutive lines in the destination image. |
pQuantInvTable |
Pointer to the quantization table for the decoder. |
These functions are declared in the ippj.h file. They operate with ROI (see Regions of Interest in Intel IPP).
These functions perform fast inverse DCT of an 8x8 block of coefficients containing non-zero components exclusively in the specified top-left part of the block. All coefficients outside the specified parts are equal to 0. The function ippiDCTQuantInv8x8LS_4x4 operates with coefficients in the 4x4 top-left quadrant of the block, ippiDCTQuantInv8x8LS_2x2 operates with coefficients in the 2x2 top-left part of the block, ippiDCTQuantInv8x8LS_1x1 operates with only DC non-zero coefficient. All functions perform dequantization of DCT coefficients and data conversion. The functions converts data from the signed Ipp16s range [-128..127] to the unsigned Ipp8u range [0..255].
The function uses a quantization table suitable for fast decoding. This table must be prepared using the function ippiQuantInvTableInit_JPEG.
ippStsNoErr |
Indicates no error. |
ippStsNullPtrErr |
Indicates an error condition if any of the specified pointers is NULL. |
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