How do I use the Canny function?

[Deleted_U_Intel]

I am using the Canny example (slightly modified) from Taylor's book on IPP and it does not work. The following is a brief listing of my code please tell me if you need more information I can post it. Please keep in mind that I am very new to IPP and hopefully this is an obvious problem. The result of the edge detected image is shrunk to 1/3 and the colors are off. Please help!

buf_ is a LocalBuffer (another class from Taylor's book)

void image_8u::edge_detection(image_8u &source)

{

int buf_size;

IppiSize dst_size;

dst_size.width = size_.width;

dst_size.height = size_.height;

ippiCannyGetSize(dst_size, &buf_size);

int tmp_size = stride_ * dst_size.height * sizeof(Ipp16s);

buf_.SetMinAlloc(tmp_size * 2 + buf_size);

Ipp16s *pTmpX = (Ipp16s*)buf_.Alloc_8u(tmp_size);

Ipp16s *pTmpY = (Ipp16s*)buf_.Alloc_8u(tmp_size);

Ipp8u *pBuffer = buf_.Alloc_8u(buf_size);

IppStatus st;

st = ippiSobel3x3_Dx_8u16s_C1R(source.p_data_, source.stride_,

pTmpX, stride_ * sizeof(Ipp16s), dst_size);

st = ippiSobel3x3_Dy_8u16s_C1R(source.p_data_, source.stride_,

pTmpY, stride_ * sizeof(Ipp16s), IPCV_ORIGIN_BL, dst_size);

st = ippiCanny_16s8u_C1R(pTmpX, stride_ * 2, pTmpY, stride_ * 2,

p_data, stride_, dst_size, 0.0, 64.0, pBuffer);

buf_.ReleaseAll();

}

[Vladimir_Dudnik]

Hi, did you look through the forum, I remember there was a question about this function? May it help you?

http://softwareforums.intel.com/ids/board/message?board.id=IPP&message.id=465

Regards,
Vladimir

[mazadic]

thanks your algo helped,

my code is as follows, which works, and hope it helps someone else:

Assume that you have the input image in Ipp8u *pGData8u_, and IppiSize iSize_ with width and height given; then the function to do canny edge is as follows which returns the answer inpProsData8u_ which is assumed to be defined earlier as Ipp8u *pProsData8u_ and allocated memory

void

FindEdge()

{

IppStatus st;

Ipp8u *ptemp8u_;

Ipp16s *pDerX;

Ipp16s *pDerY;

IppiSize b16sSize;

b16sSize.width = iSize_.width;

b16sSize.height= iSize_.height;

int bStride16s, iStride8u_; int buf_size;

ptemp8u_ = ippiMalloc_8u_C1(iSize_.width, iSize_.height, &iStride8u_);

pDerX = ippiMalloc_16s_C1(b16sSize.width, b16sSize.height, &bStride16s);

pDerY = ippiMalloc_16s_C1(b16sSize.width, b16sSize.height, &bStride16s);

st = ippiCannyGetSize(b16sSize, &buf_size);

Ipp8u *pBuffer = ippsMalloc_8u(buf_size);;

st = ippiSobel3x3_Dx_8u16s_C1R(pGData8u_, iStride8u_,pDerX, bStride16s , b16sSize);

st = ippiSobel3x3_Dy_8u16s_C1R(pGData8u_, iStride8u_,pDerY, bStride16s , IPCV_ORIGIN_TL, b16sSize);

st = ippiCanny_16s8u_C1R(pDerX, bStride16s, pDerY, bStride16s, pProsData8u_, iStride8u_, iSize_, 0.0, 64.0, pBuffer);

}

[Vladimir_Dudnik]

Hi,

thanks for sharing code here, it definetely helps someone

Regards,

Vladimir