integral_image.cpp

// OpenCV: sumpixels.cpp

template<typename T, typename ST, typename QT>
void integral_( const T* src, size_t _srcstep, ST* sum, size_t _sumstep,
                QT* sqsum, size_t _sqsumstep, ST* tilted, size_t _tiltedstep,
                Size size, int cn )
{
    int x, y, k;

    int srcstep = (int)(_srcstep/sizeof(T));
    int sumstep = (int)(_sumstep/sizeof(ST));
    int tiltedstep = (int)(_tiltedstep/sizeof(ST));
    int sqsumstep = (int)(_sqsumstep/sizeof(QT));

    size.width *= cn;

    memset( sum, 0, (size.width+cn)*sizeof(sum[0]));
    sum += sumstep + cn;

    if( sqsum )
    {
        memset( sqsum, 0, (size.width+cn)*sizeof(sqsum[0]));
        sqsum += sqsumstep + cn;
    }

    if( tilted )
    {
        memset( tilted, 0, (size.width+cn)*sizeof(tilted[0]));
        tilted += tiltedstep + cn;
    }

    if( sqsum == 0 && tilted == 0 )
    {
        for( y = 0; y < size.height; y++, src += srcstep - cn, sum += sumstep - cn )
        {
            for( k = 0; k < cn; k++, src++, sum++ )  // sum is always changed.
            {
                ST s = sum[-cn] = 0;
                for( x = 0; x < size.width; x += cn )
                {
                    s += src[x];
                    sum[x] = sum[x - sumstep] + s;
                }
            }
        }
    }
    else if( tilted == 0 )
    {
        for( y = 0; y < size.height; y++, src += srcstep - cn,
                        sum += sumstep - cn, sqsum += sqsumstep - cn )
        {
            for( k = 0; k < cn; k++, src++, sum++, sqsum++ )
            {
                ST s = sum[-cn] = 0;
                QT sq = sqsum[-cn] = 0;
                for( x = 0; x < size.width; x += cn )
                {
                    T it = src[x];
                    s += it;
                    sq += (QT)it*it;
                    ST t = sum[x - sumstep] + s;
                    QT tq = sqsum[x - sqsumstep] + sq;
                    sum[x] = t;
                    sqsum[x] = tq;
                }
            }
        }
    }
    else
    {
        AutoBuffer<ST> _buf(size.width+cn);
        ST* buf = _buf;
        ST s;
        QT sq;
        for( k = 0; k < cn; k++, src++, sum++, tilted++, buf++ )
        {
            sum[-cn] = tilted[-cn] = 0;

            for( x = 0, s = 0, sq = 0; x < size.width; x += cn )
            {
                T it = src[x];
                buf[x] = tilted[x] = it;
                s += it;
                sq += (QT)it*it;
                sum[x] = s;
                if( sqsum )
                    sqsum[x] = sq;
            }

            if( size.width == cn )
                buf[cn] = 0;

            if( sqsum )
            {
                sqsum[-cn] = 0;
                sqsum++;
            }
        }

        for( y = 1; y < size.height; y++ )
        {
            src += srcstep - cn;
            sum += sumstep - cn;
            tilted += tiltedstep - cn;
            buf += -cn;

            if( sqsum )
                sqsum += sqsumstep - cn;

            for( k = 0; k < cn; k++, src++, sum++, tilted++, buf++ )
            {
                T it = src[0];
                ST t0 = s = it;
                QT tq0 = sq = (QT)it*it;

                sum[-cn] = 0;
                if( sqsum )
                    sqsum[-cn] = 0;
                tilted[-cn] = tilted[-tiltedstep];

                sum[0] = sum[-sumstep] + t0;
                if( sqsum )
                    sqsum[0] = sqsum[-sqsumstep] + tq0;
                tilted[0] = tilted[-tiltedstep] + t0 + buf[cn];

                for( x = cn; x < size.width - cn; x += cn )
                {
                    ST t1 = buf[x];
                    buf[x - cn] = t1 + t0;
                    t0 = it = src[x];
                    tq0 = (QT)it*it;
                    s += t0;
                    sq += tq0;
                    sum[x] = sum[x - sumstep] + s;
                    if( sqsum )
                        sqsum[x] = sqsum[x - sqsumstep] + sq;
                    t1 += buf[x + cn] + t0 + tilted[x - tiltedstep - cn];
                    tilted[x] = t1;
                }

                if( size.width > cn )
                {
                    ST t1 = buf[x];
                    buf[x - cn] = t1 + t0;
                    t0 = it = src[x];
                    tq0 = (QT)it*it;
                    s += t0;
                    sq += tq0;
                    sum[x] = sum[x - sumstep] + s;
                    if( sqsum )
                        sqsum[x] = sqsum[x - sqsumstep] + sq;
                    tilted[x] = t0 + t1 + tilted[x - tiltedstep - cn];
                    buf[x] = t0;
                }

                if( sqsum )
                    sqsum++;
            }
        }
    }
}


#define DEF_INTEGRAL_FUNC(suffix, T, ST, QT) \
static void integral_##suffix( T* src, size_t srcstep, ST* sum, size_t sumstep, QT* sqsum, size_t sqsumstep, \
                              ST* tilted, size_t tiltedstep, Size size, int cn ) \
{ integral_(src, srcstep, sum, sumstep, sqsum, sqsumstep, tilted, tiltedstep, size, cn); }

DEF_INTEGRAL_FUNC(8u32s, uchar, int, double)
DEF_INTEGRAL_FUNC(8u32f64f, uchar, float, double)
DEF_INTEGRAL_FUNC(8u64f64f, uchar, double, double)
DEF_INTEGRAL_FUNC(32f32f64f, float, float, double)
DEF_INTEGRAL_FUNC(32f64f64f, float, double, double)
DEF_INTEGRAL_FUNC(64f64f64f, double, double, double)

DEF_INTEGRAL_FUNC(8u32s32f, uchar, int, float)
DEF_INTEGRAL_FUNC(8u32f32f, uchar, float, float)
DEF_INTEGRAL_FUNC(32f32f32f, float, float, float)

typedef void (*IntegralFunc)(const uchar* src, size_t srcstep, uchar* sum, size_t sumstep,
                             uchar* sqsum, size_t sqsumstep, uchar* tilted, size_t tstep,
                             Size size, int cn );