Intel® Integrated Performance Primitives (Intel® IPP) Developer Guide and Reference

ID 790148
Date 3/22/2024
Public
Document Table of Contents

Threshold

Performs the threshold operation on the elements of a vector by limiting the element values by specified value.

Syntax

IppStatus ippsThreshold_16s(const Ipp16s* pSrc, Ipp16s* pDst, int len, Ipp16s level, IppCmpOp relOp);

IppStatus ippsThreshold_32f(const Ipp32f* pSrc, Ipp32f* pDst, int len, Ipp32f level, IppCmpOp relOp);

IppStatus ippsThreshold_64f(const Ipp64f* pSrc, Ipp64f* pDst, int len, Ipp64f level, IppCmpOp relOp);

IppStatus ippsThreshold_32fc(const Ipp32fc* pSrc, Ipp32fc* pDst, int len, Ipp32f level, IppCmpOp relOp);

IppStatus ippsThreshold_64fc(const Ipp64fc* pSrc, Ipp64fc* pDst, int len, Ipp64f level, IppCmpOp relOp);

IppStatus ippsThreshold_16sc(const Ipp16sc* pSrc, Ipp16sc* pDst, int len, Ipp16s level, IppCmpOp relOp);

IppStatus ippsThreshold_16s_I(Ipp16s* pSrcDst, int len, Ipp16s level,IppCmpOp relOp);

IppStatus ippsThreshold_32f_I(Ipp32f* pSrcDst, int len, Ipp32f level, IppCmpOp relOp);

IppStatus ippsThreshold_64f_I(Ipp64f* pSrcDst, int len, Ipp64f level, IppCmpOp relOp);

IppStatus ippsThreshold_32fc_I(Ipp32fc* pSrcDst, int len, Ipp32f level, IppCmpOp relOp);

IppStatus ippsThreshold_64fc_I(Ipp64fc* pSrcDst, int len, Ipp64f level, IppCmpOp relOp);

IppStatus ippsThreshold_16sc_I(Ipp16sc* pSrcDst, int len, Ipp16s level, IppCmpOp relOp);

Include Files

ipps.h

Domain Dependencies

Headers: ippcore.h, ippvm.h

Libraries: ippcore.lib, ippvm.lib

Parameters

pSrc

Pointer to the source vector.

pDst

Pointer to the destination vector.

pSrcDst

Pointer to the source and destination vector for the in-place operation.

len

Number of elements in the vector.

level

Value used to limit each element of pSrc or pSrcDst.This parameter must always be real. For complex versions, it must be positive and represent magnitude.

relOp

Values of this argument specify which relational operator to use and whether level is an upper or lower bound for the input. The relOp must have one of the following values:

ippCmpLess Specifies the “less than” operator and level is a lower bound.

ippCmpGreater Specifies the “greater than” operator and level is an upper bound.

Description

This function performs the threshold operation on the vector pSrc by limiting each element by the threshold value level. Function operation is similar to that of the functions ippsThreshold_LT, ippsThreshold_GT but its interface contains the relOp parameter that specifies the type of the comparison operation to perform.

The in-place flavors of ippsThreshold perform the threshold operation on the vector pSrcDst by limiting each element by the threshold value level.

The relOp argument specifies which relational operator to use: when its value is ippCmpGreater - “greater than”, when ippCmpLess - “less than”, and determines whether level is an upper or lower bound for the input, respectively.

The formula for ippsThreshold called with the relOp = ippCmpLess is:



The formula for ippsThreshold called with the relOp = ippCmpGreater is:



For complex versions of the function ippsThreshold, the level argument is always real. The formula for complex ippsThreshold called with the relOp = ippCmpLess is:



The formula for complex ippsThreshold called with the relOp = ippCmpGreater is:



Application Notes

For all complex versions, level must be positive and represents a magnitude. The magnitude of the input is limited, but the phase remains unchanged. Zero-valued input is assumed to have zero phase.

A special rule is applied to the integer complex versions of the function ippsThreshold. In general, the resulting point coordinates at the complex plane are not integer. The function rounds them off to integer in such a way that the threshold operation is not performed. Thus, for the “less than” operation (with the ippCmpLess flag) the coordinates are rounded to the infinity (+Inf for positive coordinates, and -Inf for negative), and for the “greater than” operation (with the ippCmpGreater flag) the coordinates are rounded to zero.

Return Values

ippStsNoErr

Indicates no error.

ippStsNullPtrErr

Indicates an error when the pSrc, pDst, or pSrcDst pointer is NULL.

ippStsSizeErr

Indicates an error when len is less than or equal to 0.

ippStsBadArgErr

Indicates an error when relOp has an invalid value.

ippStsThreshNegLevelErr

Indicates an error when level for the complex version is negative (see appendix A "Handling of Special Cases" for more information).

Example

/*******************************************************************************
* Copyright 2015 Intel Corporation.
*
*
* This software and the related documents are Intel copyrighted materials, and your use of them is governed by
* the express license under which they were provided to you ('License'). Unless the License provides otherwise,
* you may not use, modify, copy, publish, distribute, disclose or transmit this software or the related
* documents without Intel's prior written permission.
* This software and the related documents are provided as is, with no express or implied warranties, other than
* those that are expressly stated in the License.
*******************************************************************************/

#include <stdio.h>
#include "ipp.h"

/* Next two defines are created to simplify code reading and understanding */
#define EXIT_MAIN exitLine:                                  /* Label for Exit */
#define check_sts(st) if((st) != ippStsNoErr) goto exitLine; /* Go to Exit if Intel(R) Integrated Performance Primitives (Intel(R) IPP) function returned status different from ippStsNoErr */

/* Results of ippMalloc() are not validated because Intel(R) IPP functions perform bad arguments check and will return an appropriate status  */

int main()
{
    Ipp32f pVals[] = { 1, -3, 5, -7, 18, -24, 35, 48 };
    Ipp32f pOutVals[8];
    IppStatus status;
    int i;

    printf("\nSource vector\n");
    for (i = 0; i < 8; i++) printf("%f ", pVals[i]);

    check_sts(status = ippsThreshold_32f(pVals, pOutVals, 8, 10, ippCmpGreater));

    printf("\nResult values vector\n");
    for (i = 0; i < 8; i++) printf("%f ", pOutVals[i]);

EXIT_MAIN
    printf("\nExit status %d (%s)\n", (int)status, ippGetStatusString(status));
    return (int)status;
}