C:/Media/Website/htdocs/dt2005/Src/Modules/ImageProcessor/PanoramaImageProcessor/anigauss.cpp

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#include "anigauss.h"


void YvVfilterCoef(double sigma, double *filter);
void TriggsM(double *filter, double *M);

static void f_iir_xline_filter(SRCTYPE *src, DSTTYPE *dest, int sx, int sy,
    double *filter);
static void f_iir_yline_filter(DSTTYPE *src, DSTTYPE *dest, int sx, int sy,
    double *filter);
static void f_iir_tline_filter(DSTTYPE *src, DSTTYPE *dest, int sx, int sy,
    double *filter, double tanp);
static void f_iir_derivative_filter(DSTTYPE *src, DSTTYPE *dest, int sx, int sy,
    double phi, int order);

/*
 *  the main function:
 *    anigauss(inbuf, outbuf, bufwidth, bufheight, sigma_v, sigma_u, phi,
 *       derivative_order_v, derivative_order_u);
 *
 *  v-axis = short axis
 *  u-axis = long axis
 *  phi = orientation angle in degrees
 *
 *  for example, anisotropic data smoothing:
 *    anigauss(inptr, outptr, 512, 512, 3.0, 7.0, 30.0, 0, 0);
 *
 *  or, anisotropic edge detection:
 *    anigauss(inptr, outptr, 512, 512, 3.0, 7.0, 30.0, 1, 0);
 *
 *  or, anisotropic line detection:
 *    anigauss(inptr, outptr, 512, 512, 3.0, 7.0, 30.0, 2, 0);
 *
 *  or, in-place anisotropic data smoothing:
 *    anigauss(bufptr, bufptr, 512, 512, 3.0, 7.0, 30.0, 0, 0);
 *
 */



void anigauss(SRCTYPE *input, DSTTYPE *output, int sizex, int sizey,
        double sigmav, double sigmau, double phi, int orderv, int orderu)
{
    double      filter[7];
    double sigmax, sigmay, tanp;
    double su2, sv2;
    double phirad;
    double a11, a21, a22;
    int    i;

    su2 = sigmau*sigmau;
    sv2 = sigmav*sigmav;
    phirad = phi*PI/180.;

    a11 = cos(phirad)*cos(phirad)*su2 + sin(phirad)*sin(phirad)*sv2;
    a21 = cos(phirad)*sin(phirad)*(su2-sv2);
    a22 = cos(phirad)*cos(phirad)*sv2 + sin(phirad)*sin(phirad)*su2;

    sigmax = sqrt(a11-a21*a21/a22);
    tanp = a21/a22;
    sigmay = sqrt(a22);

    /* calculate filter coefficients of x-direction*/
    YvVfilterCoef(sigmax, filter);

    /* filter in the x-direction */
    f_iir_xline_filter(input,output,sizex,sizey,filter);

    /* calculate filter coefficients in tanp-direction */
    YvVfilterCoef(sigmay, filter);

    if (tanp != 0.0) {
        /* filter in the tanp-direction */
         f_iir_tline_filter(output,output,sizex,sizey,filter, tanp);
    }
    else {
        /* isotropic filter or anisotropic filter aligned with grid */
         f_iir_yline_filter(output,output,sizex,sizey,filter);
    }

    /* do the derivative filter: [-1,0,1] rotated over phi */
    for(i=0; i<orderv; i++)
        f_iir_derivative_filter(output, output, sizex, sizey, phirad-PI/2., 1);
    for(i=0; i<orderu; i++)
        f_iir_derivative_filter(output, output, sizex, sizey, phirad, 1);
}


void YvVfilterCoef(double sigma, double *filter)
{
    /* the recipe in the Young-van Vliet paper:
     * I.T. Young, L.J. van Vliet, M. van Ginkel, Recursive Gabor filtering.
     * IEEE Trans. Sig. Proc., vol. 50, pp. 2799-2805, 2002.
     *
     * (this is an improvement over Young-Van Vliet, Sig. Proc. 44, 1995)
     */

        double q, qsq;
    double scale;
    double B, b1, b2, b3;

        /* initial values */
        double m0 = 1.16680, m1 = 1.10783, m2 = 1.40586;
        double m1sq = m1*m1, m2sq = m2*m2;

        /* calculate q */
        if(sigma < 3.556)
                q = -0.2568 + 0.5784 * sigma + 0.0561 * sigma * sigma;
        else
                q = 2.5091 + 0.9804 * (sigma - 3.556);

        qsq = q*q;

        /* calculate scale, and b[0,1,2,3] */
        scale = (m0 + q) * (m1sq + m2sq + 2*m1*q + qsq);
        b1 = -q * (2*m0*m1 + m1sq + m2sq + (2*m0 + 4*m1) * q + 3*qsq) / scale;
        b2 = qsq * (m0 + 2*m1 + 3*q) / scale;
        b3 = - qsq * q / scale;
    
        /* calculate B */
        B = (m0 * (m1sq + m2sq))/scale;

        /* fill in filter */
    filter[0] = -b3;
    filter[1] = -b2;
    filter[2] = -b1;
    filter[3] = B;
    filter[4] = -b1;
    filter[5] = -b2;
    filter[6] = -b3;
}

void TriggsM(double *filter, double *M)
{
    double scale;
    double a1, a2, a3;

    a3 = filter[0];
    a2 = filter[1];
    a1 = filter[2];

    scale = 1.0/((1.0+a1-a2+a3)*(1.0-a1-a2-a3)*(1.0+a2+(a1-a3)*a3));
    M[0] = scale*(-a3*a1+1.0-a3*a3-a2);
    M[1] = scale*(a3+a1)*(a2+a3*a1);
    M[2] = scale*a3*(a1+a3*a2);
    M[3] = scale*(a1+a3*a2);
    M[4] = -scale*(a2-1.0)*(a2+a3*a1);
    M[5] = -scale*a3*(a3*a1+a3*a3+a2-1.0);
    M[6] = scale*(a3*a1+a2+a1*a1-a2*a2);
    M[7] = scale*(a1*a2+a3*a2*a2-a1*a3*a3-a3*a3*a3-a3*a2+a3);
    M[8] = scale*a3*(a1+a3*a2);
}


/**************************************
 * the low level filtering operations *
 **************************************/

/*
   all filters work in-place on the output buffer (DSTTYPE), except for the
   xline filter, which runs over the input (SRCTYPE)
   Note that the xline filter can also work in-place, in which case src=dst
   and SRCTYPE should be DSTTYPE
*/

static void
f_iir_xline_filter(SRCTYPE *src, DSTTYPE *dest, int sx, int sy, double *filter)
{
    int      i, j;
    double   b1, b2, b3;
    double   pix, p1, p2, p3;
    double   sum, sumsq;
    double   iplus, uplus, vplus;
    double   unp, unp1, unp2;
    double   M[9];

    sumsq = filter[3];
    sum = sumsq*sumsq;

    for (i = 0; i < sy; i++) {
                /* causal filter */
        b1 = filter[2]; b2 = filter[1]; b3 = filter[0];
                p1 = *src/sumsq; p2 = p1; p3 = p1;

        iplus = src[sx-1];
        for (j = 0; j < sx; j++) {
            pix = *src++ + b1*p1 + b2*p2 + b3*p3;
            *dest++ = pix;
            p3 = p2; p2 = p1; p1 = pix; /* update history */
        }

                /* anti-causal filter */

        /* apply Triggs border condition */
        uplus = iplus/(1.0-b1-b2-b3);
        b1 = filter[4]; b2 = filter[5]; b3 = filter[6];
        vplus = uplus/(1.0-b1-b2-b3);

        unp = p1-uplus;
        unp1 = p2-uplus;
        unp2 = p3-uplus;

        TriggsM(filter, M);

        pix = M[0]*unp+M[1]*unp1+M[2]*unp2 + vplus;
        p1  = M[3]*unp+M[4]*unp1+M[5]*unp2 + vplus;
        p2  = M[6]*unp+M[7]*unp1+M[8]*unp2 + vplus;
        pix *= sum; p1 *= sum; p2 *= sum;

        *(--dest) = pix;
        p3 = p2; p2 = p1; p1 = pix;

        for (j = sx-2; j >= 0; j--) {
            pix = sum * *(--dest) + b1*p1 + b2*p2 + b3*p3;
            *dest = pix;
            p3 = p2; p2 = p1; p1 = pix;
        }
        dest += sx;
        }
}

static void
f_iir_yline_filter(DSTTYPE *src, DSTTYPE *dest, int sx, int sy, double *filter)
{
    double   *p0, *p1, *p2, *p3, *pswap;
    double   *buf0, *buf1, *buf2, *buf3;
    double   *uplusbuf;
    int      i, j;
    double   b1, b2, b3;
    double   pix;
    double   sum, sumsq;
    double   uplus, vplus;
    double   unp, unp1, unp2;
    double   M[9];

    sumsq = filter[3];
    sum = sumsq*sumsq;

    uplusbuf = (double *)malloc(sx*sizeof(*uplusbuf));

    buf0 = (double*)malloc(sx*sizeof(*buf0));
    buf1 = (double*)malloc(sx*sizeof(*buf1));
    buf2 = (double*)malloc(sx*sizeof(*buf2));
    buf3 = (double*)malloc(sx*sizeof(*buf3));

    p0 = buf0; p1 = buf1; p2 = buf2; p3 = buf3;

    /* causal filter */
    b1 = filter[2]; b2 = filter[1]; b3 = filter[0];

    /* border first line*/
    for (j = 0; j < sx; j++) {
        pix = *src++/sumsq;
                p1[j] = pix; p2[j] = pix; p3[j] = pix;
    }
    /* calc last line for Triggs boundary condition */
    src += (sy-2)*sx;
    for (j = 0; j < sx; j++)
        uplusbuf[j] = *src++/(1.0-b1-b2-b3);
    src -= sy*sx;

    for (i = 0; i < sy; i++) {
        for (j = 0; j < sx; j++) {
            pix = *src++ + b1*p1[j] + b2*p2[j] + b3*p3[j];
            *dest++ = pix;
            p0[j] = pix;
        }

        /* shift history */
                pswap = p3; p3 = p2; p2 = p1; p1 = p0; p0 = pswap;
    }


    /* anti-causal filter */

    /* apply Triggs border condition */
    b1 = filter[4]; b2 = filter[5]; b3 = filter[6];
    TriggsM(filter, M);

    /* first line */
    p0 = uplusbuf;
    for (j = sx-1; j >= 0; j--) {
        uplus = p0[j];
        vplus = uplus/(1.0-b1-b2-b3);

        unp = p1[j]-uplus;
        unp1 = p2[j]-uplus;
        unp2 = p3[j]-uplus;
        pix = M[0]*unp+M[1]*unp1+M[2]*unp2 + vplus;
        pix *= sum;
        *(--dest) = pix;
        p1[j] = pix;
        pix  = M[3]*unp+M[4]*unp1+M[5]*unp2 + vplus;
        p2[j] = pix*sum;
        pix  = M[6]*unp+M[7]*unp1+M[8]*unp2 + vplus;
        p3[j] = pix*sum;
    }

    for (i = sy-2; i >= 0; i--) {
        for (j = sx-1; j >= 0; j--) {
            pix = sum * *(--dest) + b1*p1[j] + b2*p2[j] + b3*p3[j];
            *dest = pix;
            p0[j] = pix;
        }

        /* shift history */
                pswap = p3; p3 = p2; p2 = p1; p1 = p0; p0 = pswap;
    }

    free(buf0);
    free(buf1);
    free(buf2);
    free(buf3);
    free(uplusbuf);
}


static void
f_iir_tline_filter(DSTTYPE *src, DSTTYPE *dest, int sx, int sy,
    double *filter, double tanp)
{
    double   *p0, *p1, *p2, *p3;
    double   *buf0, *buf1, *buf2, *buf3;
    double   *uplusbuf;
    int      i, j;
    double   b1, b2, b3;
    double   sum, sumsq;
    double   uplus, vplus;
    double   unp, unp1, unp2;
    double   M[9];
    double   pix, prev, val;
    double   res, prevres;
    double   xf;
    int      x;
    double   c, d;
    double   e, f;
    int      q4 = 0;

    /* check filter direction towards first or fourth quadrant */
    if (tanp <= 0.0) {
        q4 = 1;
        tanp = -tanp;
    }
    
    /* alloc buffer for Triggs boundary condition */
    uplusbuf = (double*)malloc(sx*sizeof(*uplusbuf));

    /* alloc recursion line buffers */
    buf0 = (double*)malloc((int)(sx+sy*tanp+2)*sizeof(*buf0));
    buf1 = (double*)malloc((int)(sx+sy*tanp+2)*sizeof(*buf1));
    buf2 = (double*)malloc((int)(sx+sy*tanp+2)*sizeof(*buf2));
    buf3 = (double*)malloc((int)(sx+sy*tanp+2)*sizeof(*buf3));

    if (q4) {
        buf0 += (int)(sy*tanp+1);
        buf1 += (int)(sy*tanp+1);
        buf2 += (int)(sy*tanp+1);
        buf3 += (int)(sy*tanp+1);
    }

    sumsq = filter[3];
    sum = sumsq*sumsq;

    /* causal filter */
    b1 = filter[2]; b2 = filter[1]; b3 = filter[0];

    /* first line */
    p1 = buf1; p2 = buf2; p3 = buf3;
    for (j = 0; j < sx; j++) {
        pix = *src++;
        *dest++ = pix; *p1++ = pix; *p2++ = pix; *p3++ = pix;
    }

    /* calc last line for Triggs boundary condition */
    src += (sy-2)*sx;
    for (j = 0; j < sx; j++)
        uplusbuf[j] = *src++ * sumsq/(1.0-b1-b2-b3);
    src -= (sy-1)*sx;

    x = 0;
    for (i = 1; i < sy; i++) {
        xf = i*tanp;

        /* border handling at image corner */
        if (q4) {
            p1 = buf1-x; p2 = buf2-x; p3 = buf3-x;
            for (j=1; j <= (int)(xf)-x; j++) {
                p1[-j] = p1[0];
                p2[-j] = p2[0];
                p3[-j] = p3[0];
            }
        }
        else {
            p1 = buf1+x; p2 = buf2+x; p3 = buf3+x;
            for (j=1; j <= (int)(xf)-x; j++) {
                p1[sx+j-1] = p1[sx-1];
                p2[sx+j-1] = p2[sx-1];
                p3[sx+j-1] = p3[sx-1];
            }
        }

        /* calc interpolation coefficients */
        x = (int)xf;
        c = xf-(double)x;
        d = 1.0-c;

        e = c; f = d;
        if (!q4) {
            res = d; d = c; c = res;
            res = f; f = e; e = res;
        }

        c *= sumsq; d *= sumsq;

        /* set buffers at start */
        if (q4) {
            p0 = buf0-x; p1 = buf1-x; p2 = buf2-x; p3 = buf3-x;
        }
        else {
            p0 = buf0+x; p1 = buf1+x; p2 = buf2+x; p3 = buf3+x;
        }
        prev = *src;
        prevres = sumsq*prev + b1 * *p1 + b2 * *p2 + b3 * *p3;

        /* run the filter */
        for (j = 0; j < sx; j++) {
            pix = *src++;
            val = c*pix+d*prev;
            prev = pix;

            res = val + b1 * *p1++ + b2 * *p2++ + b3 * *p3++;
            *p0++ = res;
            *dest++ = f*res+e*prevres;
            prevres = res;
        }

        /* shift history */
        p0 = buf3; buf3 = buf2; buf2 = buf1; buf1 = buf0; buf0 = p0;
    }

    /* anti-causal */

    /* apply Triggs border condition */
    b1 = filter[4]; b2 = filter[5]; b3 = filter[6];
    TriggsM(filter, M);

    /* first line */
    x = (int)((sy-1)*tanp);
    if (q4) {
        p1 = buf1+sx-x; p2 = buf2+sx-x; p3 = buf3+sx-x;
    }
    else {
        p1 = buf1+sx+x; p2 = buf2+sx+x; p3 = buf3+sx+x;
    }
    p0 = uplusbuf+sx;
    for (j = 0; j < sx; j++) {
        uplus = *(--p0);
        vplus = uplus/(1.0-b1-b2-b3);

        unp = *(--p1)-uplus;
        unp1 = *(--p2)-uplus;
        unp2 = *(--p3)-uplus;
        pix = M[0]*unp+M[1]*unp1+M[2]*unp2 + vplus;
        pix *= sumsq;
        *(--dest) = pix; *p1 = pix;
        pix  = M[3]*unp+M[4]*unp1+M[5]*unp2 + vplus;
        *p2 = pix*sumsq;
        pix  = M[6]*unp+M[7]*unp1+M[8]*unp2 + vplus;
        *p3 = pix*sumsq;
    }

    for (i = sy-2; i >= 0; i--) {
        xf = i*tanp;

        /* border handling at image corner */
        if (q4) {
            p1 = buf1-x; p2 = buf2-x; p3 = buf3-x;
            for (j=1; j <= x-(int)(xf); j++) {
                p1[sx+j-1] = p1[sx-1];
                p2[sx+j-1] = p2[sx-1];
                p3[sx+j-1] = p3[sx-1];
            }
        }
        else {
            p1 = buf1+x; p2 = buf2+x; p3 = buf3+x;
            for (j=1; j <= x-(int)(xf); j++) {
                p1[-j] = p1[0];
                p2[-j] = p2[0];
                p3[-j] = p3[0];
            }
        }

        /* calc interpolation coefficients */
        x = (int)xf;
        c = xf-(double)x;
        d = 1.0-c;

        e = c; f = d;
        c *= sumsq; d *= sumsq;

        if (!q4) {
            res = d; d = c; c = res;
            res = f; f = e; e = res;
        }

        /* set buffers at start */
        if (q4) {
            p0 = buf0+sx-x; p1 = buf1+sx-x; p2 = buf2+sx-x; p3 = buf3+sx-x;
        }
        else {
            p0 = buf0+sx+x; p1 = buf1+sx+x; p2 = buf2+sx+x; p3 = buf3+sx+x;
        }
        prev = *(dest-1);
        prevres = sumsq*prev + b1 * *(p1-1) + b2 * *(p2-1) + b3 * *(p3-1);

        /* run the filter */
        for (j = 0; j < sx; j++) {
            pix = *(--dest);
            val = d*pix+c*prev;
            prev = pix;

            res = val + b1 * *(--p1) + b2 * *(--p2) + b3 * *(--p3);
            *(--p0) = res;
            *dest = e*res+f*prevres;
            prevres = res;
        }

        /* shift history */
        p0 = buf3; buf3 = buf2; buf2 = buf1; buf1 = buf0; buf0 = p0;
    }

    if (q4) {
        buf0 -= (int)(sy*tanp+1);
        buf1 -= (int)(sy*tanp+1);
        buf2 -= (int)(sy*tanp+1);
        buf3 -= (int)(sy*tanp+1);
    }
    free(buf0);
    free(buf1);
    free(buf2);
    free(buf3);
    free(uplusbuf);
}

/* rotated [-1,0,1] derivative filter */
static void
f_iir_derivative_filter(DSTTYPE *src, DSTTYPE *dest, int sx, int sy,
    double phi, int order)
{
   int                          i, j;
   DSTTYPE   *prev, *center, *next;
   DSTTYPE   *buf, *pstore;
   double  pn, pc, pp;
   double  cn, cc, cp;
   double  nn, nc, np;
   double  cosp, sinp;

   buf = (double*)malloc(sx*sizeof(*buf));

   sinp = 0.5*sin(phi); cosp = 0.5*cos(phi);

   center = src; prev = src; next = src+sx;
   for (i = 0; i < sy; i++) {
        pstore = buf;
        pn = *prev++; cn = *center++; nn = *next++;
        pp = pn; pc = pn;
        cp = cn; cc = cn;
        np = pn; nc = nn;
        *pstore++ = cc;
        for (j = 1; j < sx; j++) {
            pn = *prev++;
            cn = *center++;
            nn = *next++;
            *dest++ = sinp*(pc-nc)+cosp*(cn-cp);
            pp = pc; pc = pn;
            cp = cc; cc = cn;
            np = pc; nc = nn;
            *pstore++ = cc;
        }
        *dest++ = sinp*(pc-nc)+cosp*(cn-cp);
        prev = buf;
        if (i==sy-2)
            next -= sx;
    }

   free(buf);
}

---