Issue with converting from 16bit signed to 8bit unsigned while decompressing and reconstructing one multi frame image.

krushnaps — Wed, 10 Aug 2011 05:53:07 GMT

Hi,

I am using intel IPP library for decompressing one multi frame image. Internally I am using "ReconstructMCURowLS" method of the the class "jpegdec.cpp" for reconstructing the JPEG. Reconstruction is successful but while converting 16bit signed to 8bit unsigned, I am geting all the "pDst8u" 0xff instead of 0x00. And resulting all colours(near to black) becomes white.

Below is the code path which is getting executed......

{

......

.......

if(m_dst.precision <= 8)

{

dstStep = curr_comp->m_cc_step;

pDst8u = curr_comp->GetCCBufferPtr(thread_id);

}

.......

..........

............

........

status = ippiReconstructPredRow_JPEG_16s_C1(

ptr,pPrevRow,pCurrRow,m_dst.width,m_ss);

.........

............

..........

........

status = ippiConvert_16s8u_C1R(pPrevRow,m_dst.width*sizeof(Ipp16s),pDst8u,dstStep,roi);

}

Here I am not getting the expected result i.e. status should be "zero".

I have doubt here, am I using the wrong method to convert from 16s to 8u? or something wrong is happening?

Can someone please help me in this topic?

Thanks and Regards

Krushna

Issue with converting from 16bit signed to 8bit unsigned while

Chao_Y_Intel — Thu, 11 Aug 2011 02:06:45 GMT

Krushna,

What is the input value for calling ippiConvert_16s8u_C1R? the value is less 0 will be convert to 0, and the value larger than 255, and will be converted to 255.

Thanks,
Chao

topic Issue with converting from 16bit signed to 8bit unsigned while in Intel® Integrated Performance Primitives

Issue with converting from 16bit signed to 8bit unsigned while decompressing and reconstructing one multi frame image.

Issue with converting from 16bit signed to 8bit unsigned while