Include Files

Domain Dependencies

Headers:

ippcore.h

,

ippvm.h

,

ipps.h

Libraries:

ippcore.lib

,

ippvm.lib

,

ipps.lib

Description

This function operates with ROI (see Regions of Interest in Intel IPP) of the size that is specified by the

ippiDCTInvInit

function.

This function performs an inverse DCT on each channel of the input image

pSrc

and writes the result into the corresponding channel of the output image buffer

pDst

. Note that the function flavor with

AC4

descriptor does not process alpha channel. This function uses the previously initialized

pDCTSpec

context structure to set the mode of calculations and retrieve support data.

The function may be used with the external work buffer

pBuffer

to avoid memory allocation within the functions. Once the work buffer is allocated, it can be used for all following calls to the functions computing DCT. As internal allocation of memory is too expensive operation and depends on operating system and/or runtime libraries used - the use of an external buffer improves performance significantly, especially for the small size transforms.

Before using the inverse DCT functions, you need to compute the size of the required buffers and the external work buffer using the

ippiDCTInvGetSize

function.