Function cvCalcArrBackProjectPatch

deps/opencv/modules/imgproc/src/histogram.cpp:2846–2916

////////////////////// B A C K   P R O J E C T   P A T C H /////////////////////////

CV_IMPL void
cvCalcArrBackProjectPatch( CvArr** arr, CvArr* dst, CvSize patch_size, CvHistogram* hist,
                           int method, double norm_factor )
{
    CvHistogram* model = 0;

    IplImage imgstub[CV_MAX_DIM], *img[CV_MAX_DIM];
    IplROI roi;
    CvMat dststub, *dstmat;
    int i, dims;
    int x, y;
    CvSize size;

    if( !CV_IS_HIST(hist))
        CV_Error( CV_StsBadArg, "Bad histogram pointer" );

    if( !arr )
        CV_Error( CV_StsNullPtr, "Null double array pointer" );

    if( norm_factor <= 0 )
        CV_Error( CV_StsOutOfRange,
                  "Bad normalization factor (set it to 1.0 if unsure)" );

    if( patch_size.width <= 0 || patch_size.height <= 0 )
        CV_Error( CV_StsBadSize, "The patch width and height must be positive" );

    dims = cvGetDims( hist->bins );
    cvNormalizeHist( hist, norm_factor );

    for( i = 0; i < dims; i++ )
    {
        CvMat stub, *mat;
        mat = cvGetMat( arr[i], &stub, 0, 0 );
        img[i] = cvGetImage( mat, &imgstub[i] );
        img[i]->roi = &roi;
    }

    dstmat = cvGetMat( dst, &dststub, 0, 0 );
    if( CV_MAT_TYPE( dstmat->type ) != CV_32FC1 )
        CV_Error( CV_StsUnsupportedFormat, "Resultant image must have 32fC1 type" );

    if( dstmat->cols != img[0]->width - patch_size.width + 1 ||
        dstmat->rows != img[0]->height - patch_size.height + 1 )
        CV_Error( CV_StsUnmatchedSizes,
            "The output map must be (W-w+1 x H-h+1), "
            "where the input images are (W x H) each and the patch is (w x h)" );

    cvCopyHist( hist, &model );

    size = cvGetMatSize(dstmat);
    roi.coi = 0;
    roi.width = patch_size.width;
    roi.height = patch_size.height;

    for( y = 0; y < size.height; y++ )
    {
        for( x = 0; x < size.width; x++ )
        {