SampleDown411LS

Creates 411 MCU with level shift from pixel-order data.

Syntax

IppStatus ippiSampleDown411LS_MCU_8u16s_C3P3R(const Ipp8u* pSrc, int srcStep, Ipp16s* pDstMCU[3]);

Parameters

pSrc	Pointer to the source image ROI.
srcStep	Distance in bytes between starts of consecutive lines in the source image.
pDstMCU	Pointer to the array of 3 pointers to the destination blocks.

Description

The function ippiSampleDown411LS_MCU is declared in the ippj.h file. It operates with ROI (see Regions of Interest in Intel IPP).

This function converts interleaved data to the full MCU with 4:1:1 downsampling. Thus, final MCU consists of six blocks - four 8x8 blocks for channel 1, one 8x8 block for channel 2, and one 8x8 block for channel 3 (see Figure “MCU Structure for Different JPEG Sampling Formats”).

Downsampling is performed by averaging the corresponding pixel values.

Additionally, this function converts data from unsigned Ipp8u range [0..255] to the signed Ipp16s range [-128..127] performing level shift operation (by subtracting 128).

Return Values

ippStsNoErr	Indicates no error.
ippStsNullPtrErr	Indicates an error condition if any of the specified pointers are NULL.
ippStsStepErr	Indicates an error condition if srcStep has a zero or negative value.