rank.c

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/*====================================================================*
 -  Copyright (C) 2001 Leptonica.  All rights reserved.
 -
 -  Redistribution and use in source and binary forms, with or without
 -  modification, are permitted provided that the following conditions
 -  are met:
 -  1. Redistributions of source code must retain the above copyright
 -     notice, this list of conditions and the following disclaimer.
 -  2. Redistributions in binary form must reproduce the above
 -     copyright notice, this list of conditions and the following
 -     disclaimer in the documentation and/or other materials
 -     provided with the distribution.
 -
 -  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 -  ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 -  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 -  A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL ANY
 -  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 -  EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 -  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 -  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 -  OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 -  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 -  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *====================================================================*/

#include "allheaders.h"

/*----------------------------------------------------------------------*
 *                           Rank order filter                          *
 *----------------------------------------------------------------------*/
PIX  *
pixRankFilter(PIX       *pixs,
              l_int32    wf,
              l_int32    hf,
              l_float32  rank)
{
l_int32  d;

    PROCNAME("pixRankFilter");

    if (!pixs)
        return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
    if (pixGetColormap(pixs) != NULL)
        return (PIX *)ERROR_PTR("pixs has colormap", procName, NULL);
    d = pixGetDepth(pixs);
    if (d != 8 && d != 32)
        return (PIX *)ERROR_PTR("pixs not 8 or 32 bpp", procName, NULL);
    if (wf < 1 || hf < 1)
        return (PIX *)ERROR_PTR("wf < 1 || hf < 1", procName, NULL);
    if (rank < 0.0 || rank > 1.0)
        return (PIX *)ERROR_PTR("rank must be in [0.0, 1.0]", procName, NULL);
    if (wf == 1 && hf == 1)   /* no-op */
        return pixCopy(NULL, pixs);

    if (d == 8)
        return pixRankFilterGray(pixs, wf, hf, rank);
    else  /* d == 32 */
        return pixRankFilterRGB(pixs, wf, hf, rank);
}


PIX  *
pixRankFilterRGB(PIX       *pixs,
                 l_int32    wf,
                 l_int32    hf,
                 l_float32  rank)
{
PIX  *pixr, *pixg, *pixb, *pixrf, *pixgf, *pixbf, *pixd;

    PROCNAME("pixRankFilterRGB");

    if (!pixs)
        return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
    if (pixGetDepth(pixs) != 32)
        return (PIX *)ERROR_PTR("pixs not 32 bpp", procName, NULL);
    if (wf < 1 || hf < 1)
        return (PIX *)ERROR_PTR("wf < 1 || hf < 1", procName, NULL);
    if (rank < 0.0 || rank > 1.0)
        return (PIX *)ERROR_PTR("rank must be in [0.0, 1.0]", procName, NULL);
    if (wf == 1 && hf == 1)   /* no-op */
        return pixCopy(NULL, pixs);

    pixr = pixGetRGBComponent(pixs, COLOR_RED);
    pixg = pixGetRGBComponent(pixs, COLOR_GREEN);
    pixb = pixGetRGBComponent(pixs, COLOR_BLUE);

    pixrf = pixRankFilterGray(pixr, wf, hf, rank);
    pixgf = pixRankFilterGray(pixg, wf, hf, rank);
    pixbf = pixRankFilterGray(pixb, wf, hf, rank);

    pixd = pixCreateRGBImage(pixrf, pixgf, pixbf);
    pixDestroy(&pixr);
    pixDestroy(&pixg);
    pixDestroy(&pixb);
    pixDestroy(&pixrf);
    pixDestroy(&pixgf);
    pixDestroy(&pixbf);
    return pixd;
}


PIX  *
pixRankFilterGray(PIX       *pixs,
                  l_int32    wf,
                  l_int32    hf,
                  l_float32  rank)
{
l_int32    w, h, d, i, j, k, m, n, rankloc, wplt, wpld, val, sum;
l_int32   *histo, *histo16;
l_uint32  *datat, *linet, *datad, *lined;
PIX       *pixt, *pixd;

    PROCNAME("pixRankFilterGray");

    if (!pixs)
        return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
    if (pixGetColormap(pixs) != NULL)
        return (PIX *)ERROR_PTR("pixs has colormap", procName, NULL);
    pixGetDimensions(pixs, &w, &h, &d);
    if (d != 8)
        return (PIX *)ERROR_PTR("pixs not 8 bpp", procName, NULL);
    if (wf < 1 || hf < 1)
        return (PIX *)ERROR_PTR("wf < 1 || hf < 1", procName, NULL);
    if (rank < 0.0 || rank > 1.0)
        return (PIX *)ERROR_PTR("rank must be in [0.0, 1.0]", procName, NULL);
    if (wf == 1 && hf == 1)   /* no-op */
        return pixCopy(NULL, pixs);

        /* For rank = 0.0, this is a grayscale erosion, and for rank = 1.0,
         * a dilation.  Grayscale morphology operations are implemented
         * for filters of odd dimension, so we dispatch to grayscale
         * morphology if both wf and hf are odd.  Otherwise, we
         * slightly adjust the rank (to get the correct behavior) and
         * use the slower rank filter here. */
    if (wf % 2 && hf % 2) {
        if (rank == 0.0)
            return pixErodeGray(pixs, wf, hf);
        else if (rank == 1.0)
            return pixDilateGray(pixs, wf, hf);
    }
    if (rank == 0.0) rank = 0.0001;
    if (rank == 1.0) rank = 0.9999;

        /* Add wf/2 to each side, and hf/2 to top and bottom of the
         * image, mirroring for accuracy and to avoid special-casing
         * the boundary. */
    if ((pixt = pixAddMirroredBorder(pixs, wf / 2, wf / 2, hf / 2, hf / 2))
        == NULL)
        return (PIX *)ERROR_PTR("pixt not made", procName, NULL);

        /* Set up the two histogram arrays. */
    histo = (l_int32 *)LEPT_CALLOC(256, sizeof(l_int32));
    histo16 = (l_int32 *)LEPT_CALLOC(16, sizeof(l_int32));
    rankloc = (l_int32)(rank * wf * hf);

        /* Place the filter center at (0, 0).  This is just a
         * convenient location, because it allows us to perform
         * the rank filter over x:(0 ... w - 1) and y:(0 ... h - 1). */
    pixd = pixCreateTemplate(pixs);
    datat = pixGetData(pixt);
    wplt = pixGetWpl(pixt);
    datad = pixGetData(pixd);
    wpld = pixGetWpl(pixd);

        /* If hf > wf, it's more efficient to use row-major scanning.
         * Otherwise, traverse the image in use column-major order.  */
    if (hf > wf) {
        for (j = 0; j < w; j++) {  /* row-major */
                /* Start each column with clean histogram arrays. */
            for (n = 0; n < 256; n++)
                histo[n] = 0;
            for (n = 0; n < 16; n++)
                histo16[n] = 0;

            for (i = 0; i < h; i++) {  /* fast scan on columns */
                    /* Update the histos for the new location */
                lined = datad + i * wpld;
                if (i == 0) {  /* do full histo */
                    for (k = 0; k < hf; k++) {
                        linet = datat + (i + k) * wplt;
                        for (m = 0; m < wf; m++) {
                            val = GET_DATA_BYTE(linet, j + m);
                            histo[val]++;
                            histo16[val >> 4]++;
                        }
                    }
                } else {  /* incremental update */
                    linet = datat + (i - 1) * wplt;
                    for (m = 0; m < wf; m++) {  /* remove top line */
                        val = GET_DATA_BYTE(linet, j + m);
                        histo[val]--;
                        histo16[val >> 4]--;
                    }
                    linet = datat + (i + hf -  1) * wplt;
                    for (m = 0; m < wf; m++) {  /* add bottom line */
                        val = GET_DATA_BYTE(linet, j + m);
                        histo[val]++;
                        histo16[val >> 4]++;
                    }
                }

                    /* Find the rank value */
                sum = 0;
                for (n = 0; n < 16; n++) {  /* search over coarse histo */
                    sum += histo16[n];
                    if (sum > rankloc) {
                        sum -= histo16[n];
                        break;
                    }
                }
                if (n == 16) {  /* avoid accessing out of bounds */
                    L_WARNING("n = 16; reducing\n", procName);
                    n = 15;
                    sum -= histo16[n];
                }
                k = 16 * n;  /* starting value in fine histo */
                for (m = 0; m < 16; m++) {
                    sum += histo[k];
                    if (sum > rankloc) {
                        SET_DATA_BYTE(lined, j, k);
                        break;
                    }
                    k++;
                }
            }
        }
    } else {  /* wf >= hf */
        for (i = 0; i < h; i++) {  /* column-major */
                /* Start each row with clean histogram arrays. */
            for (n = 0; n < 256; n++)
                histo[n] = 0;
            for (n = 0; n < 16; n++)
                histo16[n] = 0;
            lined = datad + i * wpld;
            for (j = 0; j < w; j++) {  /* fast scan on rows */
                    /* Update the histos for the new location */
                if (j == 0) {  /* do full histo */
                    for (k = 0; k < hf; k++) {
                        linet = datat + (i + k) * wplt;
                        for (m = 0; m < wf; m++) {
                            val = GET_DATA_BYTE(linet, j + m);
                            histo[val]++;
                            histo16[val >> 4]++;
                        }
                    }
                } else {  /* incremental update at left and right sides */
                    for (k = 0; k < hf; k++) {
                        linet = datat + (i + k) * wplt;
                        val = GET_DATA_BYTE(linet, j - 1);
                        histo[val]--;
                        histo16[val >> 4]--;
                        val = GET_DATA_BYTE(linet, j + wf - 1);
                        histo[val]++;
                        histo16[val >> 4]++;
                    }
                }

                    /* Find the rank value */
                sum = 0;
                for (n = 0; n < 16; n++) {  /* search over coarse histo */
                    sum += histo16[n];
                    if (sum > rankloc) {
                        sum -= histo16[n];
                        break;
                    }
                }
                if (n == 16) {  /* avoid accessing out of bounds */
                    L_WARNING("n = 16; reducing\n", procName);
                    n = 15;
                    sum -= histo16[n];
                }
                k = 16 * n;  /* starting value in fine histo */
                for (m = 0; m < 16; m++) {
                    sum += histo[k];
                    if (sum > rankloc) {
                        SET_DATA_BYTE(lined, j, k);
                        break;
                    }
                    k++;
                }
            }
        }
    }

    pixDestroy(&pixt);
    LEPT_FREE(histo);
    LEPT_FREE(histo16);
    return pixd;
}


/*----------------------------------------------------------------------*
 *                             Median filter                            *
 *----------------------------------------------------------------------*/
PIX  *
pixMedianFilter(PIX     *pixs,
                l_int32  wf,
                l_int32  hf)
{
    PROCNAME("pixMedianFilter");

    if (!pixs)
        return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
    return pixRankFilter(pixs, wf, hf, 0.5);
}


/*----------------------------------------------------------------------*
 *                Rank filter (accelerated with downscaling)            *
 *----------------------------------------------------------------------*/
PIX  *
pixRankFilterWithScaling(PIX       *pixs,
                         l_int32    wf,
                         l_int32    hf,
                         l_float32  rank,
                         l_float32  scalefactor)
{
l_int32  w, h, d, wfs, hfs;
PIX     *pix1, *pix2, *pixd;

    PROCNAME("pixRankFilterWithScaling");

    if (!pixs)
        return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
    if (pixGetColormap(pixs) != NULL)
        return (PIX *)ERROR_PTR("pixs has colormap", procName, NULL);
    d = pixGetDepth(pixs);
    if (d != 8 && d != 32)
        return (PIX *)ERROR_PTR("pixs not 8 or 32 bpp", procName, NULL);
    if (wf < 1 || hf < 1)
        return (PIX *)ERROR_PTR("wf < 1 || hf < 1", procName, NULL);
    if (rank < 0.0 || rank > 1.0)
        return (PIX *)ERROR_PTR("rank must be in [0.0, 1.0]", procName, NULL);
    if (wf == 1 && hf == 1)   /* no-op */
        return pixCopy(NULL, pixs);
    if (scalefactor < 0.2 || scalefactor > 0.7) {
        L_ERROR("invalid scale factor; no scaling used\n", procName);
        return pixRankFilter(pixs, wf, hf, rank);
    }

    pix1 = pixScaleAreaMap(pixs, scalefactor, scalefactor);
    wfs = L_MAX(1, (l_int32)(scalefactor * wf + 0.5));
    hfs = L_MAX(1, (l_int32)(scalefactor * hf + 0.5));
    pix2 = pixRankFilter(pix1, wfs, hfs, rank);
    pixGetDimensions(pixs, &w, &h, NULL);
    pixd = pixScaleToSize(pix2, w, h);
    pixDestroy(&pix1);
    pixDestroy(&pix2);
    return pixd;
}