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
  26 typedef struct sparrow_find_screen_s {
  27   IplImage *green;
  28   IplImage *working;
  29   IplImage *mask;
  30   IplImage *im;
  31 } sparrow_find_screen_t;
  32
  33
  34 /* Floodfill for find screen */
  35 static inline void
  36 expand_one_mono(int x, int y, int c,
  37     CvPoint *nexts, int *n_nexts, guint8 *im, guint8 *mask, int w, int h){
  38   guint8 p = im[y * w + x];
  39   guint8 *m = &mask[y * w + x];
  40   if (*m && (p == c)){
  41     *m = 0;
  42     nexts[*n_nexts].x = x;
  43     nexts[*n_nexts].y = y;
  44     (*n_nexts)++;
  45   }
  46 }
  47
  48 /*
  49   im: the image to be analysed
  50   mim: the mask image to be written
  51   start: a point of the right colour.
  52 */
  53
  54 static IplImage*
  55 floodfill_mono_superfast(IplImage *im, IplImage *mim, CvPoint start)
  56 {
  57   guint8 * data = (guint8 *)im->imageData;
  58   guint8 * mdata = (guint8 *)mim->imageData;
  59   int w = im->width;
  60   int h = im->height;
  61   int n_starts;
  62   int n_nexts = 0;
  63   CvPoint *starts;
  64   CvPoint *nexts;
  65
  66   //malloc 2 lists of points. These *could* be as large as the image (but never should be)
  67   void * mem = malloc_or_die(w * h * 2 * sizeof(CvPoint));
  68   starts = mem;
  69   nexts = starts + w * h;
  70   n_starts = 1;
  71   starts[0] = start;
  72
  73   while(n_starts){
  74     n_nexts = 0;
  75     int i;
  76     for (i = 0; i < n_starts; i++){
  77       int x = starts[i].x;
  78       int y = starts[i].y;
  79       int c = data[y * w + x];
  80       if (x > 0){
  81         expand_one_mono(x - 1, y, c, nexts, &n_nexts, data, mdata, w, h);
  82       }
  83       if (x < w - 1){
  84         expand_one_mono(x + 1, y, c, nexts, &n_nexts, data, mdata, w, h);
  85       }
  86       if (y > 0){
  87         expand_one_mono(x, y - 1, c, nexts, &n_nexts, data, mdata, w, h);
  88       }
  89       if (y < h - 1){
  90         expand_one_mono(x, y + 1, c, nexts, &n_nexts, data, mdata, w, h);
  91       }
  92     }
  93     CvPoint *tmp = starts;
  94     starts = nexts;
  95     nexts = tmp;
  96     n_starts = n_nexts;
  97   }
  98   free(mem);
  99   return im;
 100 }
 101
 102
 103
 104
 105
 106
 107 /* find a suitable threshold level by looking at the histogram of a monochrome
 108    image */
 109 static int
 110 find_edges_threshold(IplImage *im)
 111 {
 112   int w = im->width;
 113   int h = im->height;
 114   CvSize small_size = {w / 8, h / 8};
 115   IplImage *small = cvCreateImage(small_size, IPL_DEPTH_8U, 1); /*for quicker histogram (stupid, perhaps?)*/
 116   cvResize(im, small, CV_INTER_NN);
 117   int hist_size[] = {255};
 118   float range[] = {0, 255};
 119   float *ranges[] = {range};
 120   CvHistogram* hist = cvCreateHist(1, hist_size, CV_HIST_ARRAY, ranges, 1);
 121   cvCalcHist(&small, hist, 0, NULL);
 122
 123   int pixels = small->width * small->height;
 124   int min_black = pixels / 16;
 125   int max_black = pixels / 2;
 126   int totals[256] = {0};
 127
 128   int best_d = pixels + 1;
 129   int best_t = 0;
 130
 131   /* look for a low region in the histogram between the two peaks.
 132      (big assumption: two peaks, with most in whiter peak) */
 133   int total = 0;
 134   for (int i = 0; i < 255; i++){
 135     int v = (int)cvQueryHistValue_1D(hist, i);
 136     total += v;
 137     totals[i] = total;
 138     if (total >= min_black){
 139       if (i >= 5){
 140         int diff = total - totals[i - 5];
 141         if (diff < best_d){
 142           best_d = diff;
 143           best_t = i - 2;
 144         }
 145         if (total >= max_black){
 146           break;
 147         }
 148       }
 149     }
 150   }
 151   GST_DEBUG("found best threshold %d -- %d pixel change at %d/%d pixels\n",
 152       best_t, best_d, totals[best_t], pixels);
 153
 154   cvReleaseImage(&small);
 155   cvReleaseHist(&hist);
 156
 157   return best_t;
 158 }
 159
 160
 161 /* a minature state progression within this one, in case the processing is too
 162    much for one frame.*/
 163 INVISIBLE sparrow_state
 164 mode_find_screen(GstSparrow *sparrow, guint8 *in, guint8 *out){
 165   sparrow->countdown--;
 166   GST_DEBUG("in find_screen with countdown %d\n", sparrow->countdown);
 167   sparrow_find_screen_t *finder = (sparrow_find_screen_t *)sparrow->helper_struct;
 168   IplImage *im = finder->im;
 169   IplImage *green = finder->green;
 170   IplImage *working = finder->working;
 171   IplImage *mask = finder->mask;
 172   /* size is 1 byte per pixel, not 4! */
 173   size_t size = sparrow->in.pixcount;
 174   CvPoint middle, corner;
 175   switch (sparrow->countdown){
 176   case 2:
 177     /* time to look and see if the screen is there.
 178        Look at the histogram of a single channel. */
 179     im->imageData = (char*)in;
 180     guint32 gshift = sparrow->in.gshift;
 181     cvSplit(im,
 182         (gshift == 24) ? green : NULL,
 183         (gshift == 16) ? green : NULL,
 184         (gshift ==  8) ? green : NULL,
 185         (gshift ==  0) ? green : NULL);
 186     int best_t = find_edges_threshold(green);
 187     /*XXX if best_t is wrong, add to sparrow->countdown: probably the light is
 188       not really on.  But what counts as wrong? */
 189     cvCmpS(green, best_t, mask, CV_CMP_GT);
 190     goto black;
 191   case 1:
 192     /* floodfill where the screen is, removing outlying bright spots*/
 193     middle = (CvPoint){sparrow->in.width / 2, sparrow->in.height / 2};
 194     memset(working->imageData, 255, size);
 195     floodfill_mono_superfast(mask, working, middle);
 196     goto black;
 197   case 0:
 198     /* floodfill the border, removing onscreen dirt.*/
 199     corner = (CvPoint){0, 0};
 200     memset(mask->imageData, 255, size);
 201     floodfill_mono_superfast(working, mask, corner);
 202     sparrow->screenmask = (guint8*)mask->imageData;
 203     cvReleaseImage(&(finder->green));
 204     cvReleaseImage(&(finder->working));
 205     goto finish;
 206   default:
 207     /*send white and wait for the picture to arrive back. */
 208     memset(out, 255, sparrow->out.size);
 209     return SPARROW_STATUS_QUO;
 210   }
 211  black:
 212   memset(out, 0, sparrow->out.size);
 213   return SPARROW_STATUS_QUO;
 214  finish:
 215   memset(out, 0, sparrow->out.size);
 216   finalise_find_screen(sparrow);
 217   return SPARROW_NEXT_STATE;
 218 }
 219
 220 INVISIBLE void
 221 finalise_find_screen(GstSparrow *sparrow){
 222   sparrow_find_screen_t *finder = (sparrow_find_screen_t *)sparrow->helper_struct;
 223   cvReleaseImage(&finder->green);
 224   cvReleaseImage(&finder->working);
 225   cvReleaseImageHeader(&finder->mask);
 226   cvReleaseImageHeader(&finder->im);
 227   free(finder);
 228 }
 229
 230 INVISIBLE void
 231 init_find_screen(GstSparrow *sparrow){
 232   sparrow_find_screen_t *finder = zalloc_aligned_or_die(sizeof(sparrow_find_screen_t));
 233   sparrow->helper_struct = (void *)finder;
 234   sparrow->countdown = sparrow->lag + 4;
 235   CvSize size = {sparrow->in.width, sparrow->in.height};
 236   finder->green = cvCreateImage(size, IPL_DEPTH_8U, 1);
 237   finder->working = cvCreateImage(size, IPL_DEPTH_8U, 1);
 238
 239   finder->im = cvCreateImageHeader(size, IPL_DEPTH_8U, PIXSIZE);
 240   cvInitImageHeader(finder->im, size, IPL_DEPTH_8U, PIXSIZE, 0, 8);
 241
 242   finder->mask = cvCreateImageHeader(size, IPL_DEPTH_8U, 1);
 243   cvInitImageHeader(finder->mask, size, IPL_DEPTH_8U, 1, 0, 8);
 244   finder->mask->imageData = (char *)sparrow->screenmask;
 245 }
 246