floodfill.c

   1 /* Copyright (C) <2010> Douglas Bagnall <douglas@halo.gen.nz>
   2  *
   3  * This library is free software; you can redistribute it and/or
   4  * modify it under the terms of the GNU Library General Public
   5  * License as published by the Free Software Foundation; either
   6  * version 2 of the License, or (at your option) any later version.
   7  *
   8  * This library is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * Library General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU Library General Public
  14  * License along with this library; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 02111-1307, USA.
  17  */
  18
  19 #include "sparrow.h"
  20 #include "gstsparrow.h"
  21
  22 #include <string.h>
  23 #include <math.h>
  24
  25 #define STUPID_DEBUG_TRICK 1
  26
  27 typedef struct sparrow_find_screen_s {
  28   IplImage *green;
  29   IplImage *working;
  30   IplImage *mask;
  31   IplImage *im;
  32 } sparrow_find_screen_t;
  33
  34
  35 /* Floodfill for find screen */
  36 static inline void
  37 expand_one_mono(int x, int y, int c,
  38     CvPoint *nexts, int *n_nexts, guint8 *im, guint8 *mask, int w, int h){
  39   guint8 p = im[y * w + x];
  40   guint8 *m = &mask[y * w + x];
  41   if (*m && (p == c)){
  42     *m = 0;
  43     nexts[*n_nexts].x = x;
  44     nexts[*n_nexts].y = y;
  45     (*n_nexts)++;
  46   }
  47 }
  48
  49 /*
  50   im: the image to be analysed
  51   mim: the mask image to be written
  52   start: a point of the right colour.
  53 */
  54
  55 static IplImage*
  56 floodfill_mono_superfast(IplImage *im, IplImage *mim, CvPoint start)
  57 {
  58   guint8 * data = (guint8 *)im->imageData;
  59   guint8 * mdata = (guint8 *)mim->imageData;
  60   int w = im->width;
  61   int h = im->height;
  62   int n_starts;
  63   int n_nexts = 0;
  64   CvPoint *starts;
  65   CvPoint *nexts;
  66
  67   //malloc 2 lists of points. These *could* be as large as the image (but never should be)
  68   void * mem = malloc_or_die(w * h * 2 * sizeof(CvPoint));
  69   starts = mem;
  70   nexts = starts + w * h;
  71   n_starts = 1;
  72   starts[0] = start;
  73
  74   while(n_starts){
  75     n_nexts = 0;
  76     int i;
  77     for (i = 0; i < n_starts; i++){
  78       int x = starts[i].x;
  79       int y = starts[i].y;
  80       int c = data[y * w + x];
  81       if (x > 0){
  82         expand_one_mono(x - 1, y, c, nexts, &n_nexts, data, mdata, w, h);
  83       }
  84       if (x < w - 1){
  85         expand_one_mono(x + 1, y, c, nexts, &n_nexts, data, mdata, w, h);
  86       }
  87       if (y > 0){
  88         expand_one_mono(x, y - 1, c, nexts, &n_nexts, data, mdata, w, h);
  89       }
  90       if (y < h - 1){
  91         expand_one_mono(x, y + 1, c, nexts, &n_nexts, data, mdata, w, h);
  92       }
  93     }
  94     CvPoint *tmp = starts;
  95     starts = nexts;
  96     nexts = tmp;
  97     n_starts = n_nexts;
  98   }
  99   free(mem);
 100   return im;
 101 }
 102
 103
 104
 105
 106
 107
 108 /* find a suitable threshold level by looking at the histogram of a monochrome
 109    image */
 110 static int
 111 find_edges_threshold(IplImage *im)
 112 {
 113   int w = im->width;
 114   int h = im->height;
 115   CvSize small_size = {w / 4, h / 4};
 116   IplImage *small = cvCreateImage(small_size, IPL_DEPTH_8U, 1); /*for quicker histogram (stupid, perhaps?)*/
 117   cvResize(im, small, CV_INTER_NN);
 118   int hist_size[] = {255};
 119   float range[] = {0, 255};
 120   float *ranges[] = {range};
 121   CvHistogram* hist = cvCreateHist(1, hist_size, CV_HIST_ARRAY, ranges, 1);
 122   cvCalcHist(&small, hist, 0, NULL);
 123
 124   int pixels = small->width * small->height;
 125   int min_black = pixels / 16;
 126   int max_black = pixels * 3 / 4;
 127   int totals[256] = {0};
 128
 129   int best_d = pixels + 1;
 130   int best_t = 0;
 131
 132   /* look for a low region in the histogram between the two peaks.
 133      (big assumption: two peaks, with most in whiter peak) */
 134   int total = 0;
 135   for (int i = 0; i < 255; i++){
 136     int v = (int)cvQueryHistValue_1D(hist, i);
 137     total += v;
 138     totals[i] = total;
 139     if (total >= min_black){
 140       if (i >= 5){
 141         int diff = total - totals[i - 5];
 142         if (diff < best_d){
 143           best_d = diff;
 144           best_t = i - 2;
 145         }
 146         if (total >= max_black){
 147           break;
 148         }
 149       }
 150     }
 151   }
 152   GST_DEBUG("found best threshold %d -- %d pixel change at %d/%d pixels\n",
 153       best_t, best_d, totals[best_t], pixels);
 154   //MAYBE_DEBUG_IPL(small);
 155   cvReleaseImage(&small);
 156   cvReleaseHist(&hist);
 157
 158   return best_t;
 159 }
 160
 161
 162 /* a minature state progression within this one, in case the processing is too
 163    much for one frame.*/
 164 INVISIBLE sparrow_state
 165 mode_find_screen(GstSparrow *sparrow, guint8 *in, guint8 *out){
 166   sparrow->countdown--;
 167   GST_DEBUG("in find_screen with countdown %d\n", sparrow->countdown);
 168   sparrow_find_screen_t *finder = (sparrow_find_screen_t *)sparrow->helper_struct;
 169   IplImage *im = finder->im;
 170   IplImage *green = finder->green;
 171   IplImage *working = finder->working;
 172   IplImage *mask = finder->mask;
 173   /* size is 1 byte per pixel, not 4! */
 174   size_t size = sparrow->in.pixcount;
 175   CvPoint middle, corner;
 176   switch (sparrow->countdown){
 177   case 2:
 178     /* time to look and see if the screen is there.
 179        Look at the histogram of a single channel. */
 180     im->imageData = (char*)in;
 181     guint32 gshift = sparrow->in.gshift;
 182     cvSplit(im,
 183         (gshift == 24) ? green : NULL,
 184         (gshift == 16) ? green : NULL,
 185         (gshift ==  8) ? green : NULL,
 186         (gshift ==  0) ? green : NULL);
 187     //int best_t = find_edges_threshold(green);
 188     /*XXX if best_t is wrong, add to sparrow->countdown: probably the light is
 189       not really on.  But what counts as wrong? */
 190     //
 191     //cvCmpS(green, best_t, mask, CV_CMP_GT);
 192     cvCanny(green, mask, 100, 170, 3);
 193     MAYBE_DEBUG_IPL(mask);
 194     goto black;
 195   case 1:
 196     /* floodfill where the screen is, removing outlying bright spots*/
 197     middle = (CvPoint){sparrow->in.width / 2, sparrow->in.height / 2};
 198     memset(working->imageData, 255, size);
 199     floodfill_mono_superfast(mask, working, middle);
 200     MAYBE_DEBUG_IPL(working);
 201     goto black;
 202   case 0:
 203     /* floodfill the border, removing onscreen dirt.*/
 204     corner = (CvPoint){0, 0};
 205     memset(mask->imageData, 255, size);
 206     floodfill_mono_superfast(working, mask, corner);
 207 #if STUPID_DEBUG_TRICK
 208     cvErode(mask, mask, NULL, 9);
 209 #endif
 210     MAYBE_DEBUG_IPL(mask);
 211     goto finish;
 212   default:
 213     /*send white and wait for the picture to arrive back. */
 214     memset(out, 255, sparrow->out.size);
 215     return SPARROW_STATUS_QUO;
 216   }
 217  black:
 218   memset(out, 0, sparrow->out.size);
 219   return SPARROW_STATUS_QUO;
 220  finish:
 221   memset(out, 0, sparrow->out.size);
 222   return SPARROW_NEXT_STATE;
 223 }
 224
 225 INVISIBLE void
 226 finalise_find_screen(GstSparrow *sparrow){
 227   sparrow_find_screen_t *finder = (sparrow_find_screen_t *)sparrow->helper_struct;
 228   GST_DEBUG("finalise_find_screen: green %p, working %p, mask %p, im %p finder %p\n",
 229       finder->green, finder->working, finder->mask, finder->im, finder);
 230   cvReleaseImage(&finder->green);
 231   cvReleaseImage(&finder->working);
 232   cvReleaseImageHeader(&finder->mask);
 233   cvReleaseImageHeader(&finder->im);
 234   free(finder);
 235 }
 236
 237 INVISIBLE void
 238 init_find_screen(GstSparrow *sparrow){
 239   sparrow_find_screen_t *finder = zalloc_aligned_or_die(sizeof(sparrow_find_screen_t));
 240   sparrow->helper_struct = (void *)finder;
 241   sparrow->countdown = sparrow->lag + 5;
 242   CvSize size = {sparrow->in.width, sparrow->in.height};
 243   finder->green = cvCreateImage(size, IPL_DEPTH_8U, 1);
 244   finder->working = cvCreateImage(size, IPL_DEPTH_8U, 1);
 245
 246   finder->im = init_ipl_image(&sparrow->in, PIXSIZE);
 247   finder->mask  = init_ipl_image(&sparrow->in, 1);
 248
 249   finder->mask->imageData = (char *)sparrow->screenmask;
 250   GST_DEBUG("init_find_screen: green %p, working %p, mask %p, im %p finder %p\n",
 251       finder->green, finder->working, finder->mask, finder->im, finder);
 252 }
 253