topic Re: access pixel data allocated by IppiMalloc? in Intel® Integrated Performance Primitives

access pixel data allocated by IppiMalloc?

ctozlm — Mon, 28 Apr 2008 04:19:19 GMT

Is there anyone can tell me that how can I access the pixel data allocated by IppiMalloc.
I just wondering how to use the pStepBytes variable returned by IppiMalloc. If I just want to access a pixel, can I use pStepBytes as the width of the 2d array.
actually, I need to get the max value from a matrix. how should I do that? I attach some codes to illustrate my doubt.

int nImageSqureStep;
float* pImageSquare = ippiMalloc_32f_C1(szImage.width,szImage.height,&nImageSqureStep);
ippiSqr_32f_C1R(src,szImage.width*4,pImageSquare,nImageSqureStep,szImage);

How should I get access the pixel of pImageSqaure , for example
for (int row=0;row {
for (int col=0;col {
if (pImageSquare[row*nImageSqureStep+col]<)
}
}

it tell me wrong when it was executed and I gurantee that other part code is correct. So I think the problem is how to acess the pixel. and how to use the width is a problem.

Is there any other good way to get max value from the pImageSquare Array?

Thanks.

Re: access pixel data allocated by IppiMalloc?

ctozlm — Mon, 28 Apr 2008 07:08:09 GMT

I just fix that with
pImageSquare[row*nImageSqureStep/4+col]

But I am still wondering about the correctness of the above access.
will it bring correct result? nImageSquareStep is larger than the true width of the pImageSquare image?

Re: access pixel data allocated by IppiMalloc?

ctozlm — Fri, 02 May 2008 01:09:15 GMT

Is there anyone who can help me with that problem?Thanks.

How to access the pixel in IPP

Re: access pixel data allocated by IppiMalloc?

Ivan_Z_Intel — Mon, 05 May 2008 06:12:10 GMT

float max = *pImageSquare;

float *pTmp;

for ( int row = 0; row < szImage.height; row++ ) {

pTmp = (float *)( (char *)pImageSquare + nImageSquareStep * row );

for ( int col = 0; col < szImage.width; col++ ) {

if ( pTmp[col] > max ) max = pTmp[col];

}

but better

float max;

ippiMax_32f_C1R( [ImageSquare, nImageSquareStep, szImage, &max );