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#include "_cv.h"

void
icvCrossCorr( const CvArr* _img, const CvArr* _templ, CvArr* _corr, CvPoint anchor )
{
    const double block_scale = 4.5;
    const int min_block_size = 256;
    CvMat* dft_img = 0;
    CvMat* dft_templ = 0;
    void* buf = 0;
    
    CV_FUNCNAME( "icvCrossCorr" );
    
    __BEGIN__;

    CvMat istub, *img = (CvMat*)_img;
    CvMat tstub, *templ = (CvMat*)_templ;
    CvMat cstub, *corr = (CvMat*)_corr;
    CvMat sstub, dstub, *src, *dst, temp;
    CvSize dftsize, blocksize;
    CvMat* planes[] = { 0, 0, 0, 0 };
    int x, y, i, yofs, buf_size = 0;
    int depth, templ_depth, corr_depth, max_depth = CV_32F, cn, templ_cn, corr_cn;

    CV_CALL( img = cvGetMat( img, &istub ));
    CV_CALL( templ = cvGetMat( templ, &tstub ));
    CV_CALL( corr = cvGetMat( corr, &cstub ));

    if( CV_MAT_DEPTH( img->type ) != CV_8U &&
        CV_MAT_DEPTH( img->type ) != CV_16U &&
        CV_MAT_DEPTH( img->type ) != CV_32F )
        CV_ERROR( CV_StsUnsupportedFormat,
        "The function supports only 8u, 16u and 32f data types" );

    if( !CV_ARE_DEPTHS_EQ( img, templ ) && CV_MAT_DEPTH( templ->type ) != CV_32F )
        CV_ERROR( CV_StsUnsupportedFormat,
        "Template (kernel) must be of the same depth as the input image, or be 32f" );
    
    if( !CV_ARE_DEPTHS_EQ( img, corr ) && CV_MAT_DEPTH( corr->type ) != CV_32F &&
        CV_MAT_DEPTH( corr->type ) != CV_64F )
        CV_ERROR( CV_StsUnsupportedFormat,
        "The output image must have the same depth as the input image, or be 32f/64f" );

    if( (!CV_ARE_CNS_EQ( img, corr ) || CV_MAT_CN(templ->type) > 1) &&
        (CV_MAT_CN( corr->type ) > 1 || !CV_ARE_CNS_EQ( img, templ)) )
        CV_ERROR( CV_StsUnsupportedFormat,
        "The output must have the same number of channels as the input (when the template has 1 channel), "
        "or the output must have 1 channel when the input and the template have the same number of channels" );

    depth = CV_MAT_DEPTH(img->type);
    cn = CV_MAT_CN(img->type);
    templ_depth = CV_MAT_DEPTH(templ->type);
    templ_cn = CV_MAT_CN(templ->type);
    corr_depth = CV_MAT_DEPTH(corr->type);
    corr_cn = CV_MAT_CN(corr->type);
    max_depth = MAX( max_depth, templ_depth );
    max_depth = MAX( max_depth, depth );
    max_depth = MAX( max_depth, corr_depth );
    if( depth > CV_8U )
        max_depth = CV_64F;

    if( img->cols < templ->cols || img->rows < templ->rows )
        CV_ERROR( CV_StsUnmatchedSizes,
        "Such a combination of image and template/filter size is not supported" );

    if( corr->rows > img->rows + templ->rows - 1 ||
        corr->cols > img->cols + templ->cols - 1 )
        CV_ERROR( CV_StsUnmatchedSizes,
        "output image should not be greater than (W + w - 1)x(H + h - 1)" );

    blocksize.width = cvRound(templ->cols*block_scale);
    blocksize.width = MAX( blocksize.width, min_block_size - templ->cols + 1 );
    blocksize.width = MIN( blocksize.width, corr->cols );
    blocksize.height = cvRound(templ->rows*block_scale);
    blocksize.height = MAX( blocksize.height, min_block_size - templ->rows + 1 );
    blocksize.height = MIN( blocksize.height, corr->rows );

    dftsize.width = cvGetOptimalDFTSize(blocksize.width + templ->cols - 1);
    if( dftsize.width == 1 )
        dftsize.width = 2;
    dftsize.height = cvGetOptimalDFTSize(blocksize.height + templ->rows - 1);
    if( dftsize.width <= 0 || dftsize.height <= 0 )
        CV_ERROR( CV_StsOutOfRange, "the input arrays are too big" );

    // recompute block size
    blocksize.width = dftsize.width - templ->cols + 1;
    blocksize.width = MIN( blocksize.width, corr->cols );
    blocksize.height = dftsize.height - templ->rows + 1;
    blocksize.height = MIN( blocksize.height, corr->rows );

    CV_CALL( dft_img = cvCreateMat( dftsize.height, dftsize.width, max_depth ));
    CV_CALL( dft_templ = cvCreateMat( dftsize.height*templ_cn, dftsize.width, max_depth ));

    if( templ_cn > 1 && templ_depth != max_depth )
        buf_size = templ->cols*templ->rows*CV_ELEM_SIZE(templ_depth);

    if( cn > 1 && depth != max_depth )
        buf_size = MAX( buf_size, (blocksize.width + templ->cols - 1)*
            (blocksize.height + templ->rows - 1)*CV_ELEM_SIZE(depth));

    if( (corr_cn > 1 || cn > 1) && corr_depth != max_depth )
        buf_size = MAX( buf_size, blocksize.width*blocksize.height*CV_ELEM_SIZE(corr_depth));

    if( buf_size > 0 )
        CV_CALL( buf = cvAlloc(buf_size) );

    // compute DFT of each template plane
    for( i = 0; i < templ_cn; i++ )
    {
        yofs = i*dftsize.height;

        src = templ;
        dst = cvGetSubRect( dft_templ, &dstub, cvRect(0,yofs,templ->cols,templ->rows));
    
        if( templ_cn > 1 )
        {
            planes[i] = templ_depth == max_depth ? dst :
                cvInitMatHeader( &temp, templ->rows, templ->cols, templ_depth, buf );
            cvSplit( templ, planes[0], planes[1], planes[2], planes[3] );
            src = planes[i];
            planes[i] = 0;
        }

        if( dst != src )
            cvConvert( src, dst );

        if( dft_templ->cols > templ->cols )
        {
            cvGetSubRect( dft_templ, dst, cvRect(templ->cols, yofs,
                          dft_templ->cols - templ->cols, templ->rows) );
            cvZero( dst );
        }
        cvGetSubRect( dft_templ, dst, cvRect(0,yofs,dftsize.width,dftsize.height) );
        cvDFT( dst, dst, CV_DXT_FORWARD + CV_DXT_SCALE, templ->rows );
    }

    // calculate correlation by blocks
    for( y = 0; y < corr->rows; y += blocksize.height )
    {
        for( x = 0; x < corr->cols; x += blocksize.width )
        {
            CvSize csz = { blocksize.width, blocksize.height }, isz;
            int x0 = x - anchor.x, y0 = y - anchor.y;
            int x1 = MAX( 0, x0 ), y1 = MAX( 0, y0 ), x2, y2;
            csz.width = MIN( csz.width, corr->cols - x );
            csz.height = MIN( csz.height, corr->rows - y );
            isz.width = csz.width + templ->cols - 1;
            isz.height = csz.height + templ->rows - 1;
            x2 = MIN( img->cols, x0 + isz.width );
            y2 = MIN( img->rows, y0 + isz.height );
            
            for( i = 0; i < cn; i++ )
            {
                CvMat dstub1, *dst1;
                yofs = i*dftsize.height;

                src = cvGetSubRect( img, &sstub, cvRect(x1,y1,x2-x1,y2-y1) );
                dst = cvGetSubRect( dft_img, &dstub, cvRect(0,0,isz.width,isz.height) );
                dst1 = dst;
                
                if( x2 - x1 < isz.width || y2 - y1 < isz.height )
                    dst1 = cvGetSubRect( dft_img, &dstub1,
                        cvRect( x1 - x0, y1 - y0, x2 - x1, y2 - y1 ));

                if( cn > 1 )
                {
                    planes[i] = dst1;
                    if( depth != max_depth )
                        planes[i] = cvInitMatHeader( &temp, y2 - y1, x2 - x1, depth, buf );
                    cvSplit( src, planes[0], planes[1], planes[2], planes[3] );
                    src = planes[i];
                    planes[i] = 0;
                }

                if( dst1 != src )
                    cvConvert( src, dst1 );

                if( dst != dst1 )
                    cvCopyMakeBorder( dst1, dst, cvPoint(x1 - x0, y1 - y0), IPL_BORDER_REPLICATE );

                if( dftsize.width > isz.width )
                {
                    cvGetSubRect( dft_img, dst, cvRect(isz.width, 0,
                          dftsize.width - isz.width,dftsize.height) );
                    cvZero( dst );
                }

                cvDFT( dft_img, dft_img, CV_DXT_FORWARD, isz.height );
                cvGetSubRect( dft_templ, dst,
                    cvRect(0,(templ_cn>1?yofs:0),dftsize.width,dftsize.height) );

                cvMulSpectrums( dft_img, dst, dft_img, CV_DXT_MUL_CONJ );
                cvDFT( dft_img, dft_img, CV_DXT_INVERSE, csz.height );

                src = cvGetSubRect( dft_img, &sstub, cvRect(0,0,csz.width,csz.height) );
                dst = cvGetSubRect( corr, &dstub, cvRect(x,y,csz.width,csz.height) );

                if( corr_cn > 1 )
                {
                    planes[i] = src;
                    if( corr_depth != max_depth )
                    {
                        planes[i] = cvInitMatHeader( &temp, csz.height, csz.width, corr_depth, buf );
                        cvConvert( src, planes[i] );
                    }
                    cvMerge( planes[0], planes[1], planes[2], planes[3], dst );
                    planes[i] = 0;                    
                }
                else
                {
                    if( i == 0 )
                        cvConvert( src, dst );
                    else
                    {
                        if( max_depth > corr_depth )
                        {
                            cvInitMatHeader( &temp, csz.height, csz.width, corr_depth, buf );
                            cvConvert( src, &temp );
                            src = &temp;
                        }
                        cvAcc( src, dst );
                    }
                }
            }
        }
    }

    __END__;

    cvReleaseMat( &dft_img );
    cvReleaseMat( &dft_templ );
    cvFree( &buf );
}

/* End of file. */