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/* Copyright (c) 1997 Regents of the University of California */ |
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|
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#ifndef lint |
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static char SCCSid[] = "$SunId$ LBL"; |
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#endif |
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|
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/* |
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* Routines for computing and applying brightness mapping. |
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*/ |
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|
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#include "pcond.h" |
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|
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|
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#define CVRATIO 0.025 /* fraction of samples allowed > env. */ |
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|
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#define exp10(x) exp(2.302585093*(x)) |
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|
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float modhist[HISTRES]; /* modified histogram */ |
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double mhistot; /* modified histogram total */ |
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float cumf[HISTRES+1]; /* cumulative distribution function */ |
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|
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|
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getfixations(fp) /* load fixation history list */ |
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FILE *fp; |
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{ |
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#define FIXHUNK 128 |
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RESOLU fvres; |
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int pos[2]; |
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register int px, py, i; |
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/* initialize our resolution struct */ |
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if ((fvres.or=inpres.or)&YMAJOR) { |
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fvres.xr = fvxr; |
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fvres.yr = fvyr; |
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} else { |
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fvres.xr = fvyr; |
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fvres.yr = fvxr; |
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} |
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/* read each picture position */ |
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while (fscanf(fp, "%d %d", &pos[0], &pos[1]) == 2) { |
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/* convert to closest index in foveal image */ |
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loc2pix(pos, &fvres, |
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(pos[0]+.5)/inpres.xr, (pos[1]+.5)/inpres.yr); |
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/* include nine neighborhood samples */ |
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for (px = pos[0]-1; px <= pos[0]+1; px++) { |
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if (px < 0 || px >= fvxr) |
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continue; |
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for (py = pos[1]-1; py <= pos[1]+1; py++) { |
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if (py < 0 || py >= fvyr) |
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continue; |
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for (i = nfixations; i-- > 0; ) |
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if (fixlst[i][0] == px && |
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fixlst[i][1] == py) |
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break; |
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if (i >= 0) |
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continue; /* already there */ |
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if (nfixations % FIXHUNK == 0) { |
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if (nfixations) |
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fixlst = (short (*)[2]) |
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realloc((char *)fixlst, |
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(nfixations+FIXHUNK)* |
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2*sizeof(short)); |
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else |
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fixlst = (short (*)[2])malloc( |
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FIXHUNK*2*sizeof(short) |
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); |
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if (fixlst == NULL) |
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syserror("malloc"); |
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} |
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fixlst[nfixations][0] = px; |
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fixlst[nfixations][1] = py; |
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nfixations++; |
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} |
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} |
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} |
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if (!feof(fp)) { |
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fprintf(stderr, "%s: format error reading fixation data\n", |
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progname); |
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exit(1); |
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} |
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#undef FIXHUNK |
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} |
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|
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|
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double |
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centprob(x, y) /* center-weighting probability function */ |
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int x, y; |
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{ |
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double xr, yr, p; |
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/* paraboloid, 0 at 90 degrees from center */ |
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xr = (x - .5*(fvxr-1))/90.; /* 180 degree fisheye has fv?r == 90 */ |
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yr = (y - .5*(fvyr-1))/90.; |
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p = 1. - xr*xr - yr*yr; |
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return(p < 0. ? 0. : p); |
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} |
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|
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|
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comphist() /* create foveal sampling histogram */ |
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{ |
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double l, b, w, lwmin, lwmax; |
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register int x, y; |
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|
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lwmin = 1e10; /* find extrema */ |
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lwmax = 0.; |
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for (y = 0; y < fvyr; y++) |
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for (x = 0; x < fvxr; x++) { |
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l = plum(fovscan(y)[x]); |
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if (l < lwmin) lwmin = l; |
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if (l > lwmax) lwmax = l; |
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} |
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lwmax *= 1.01; |
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if (lwmax > LMAX) |
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lwmax = LMAX; |
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bwmax = Bl(lwmax); |
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if (lwmin < LMIN) { |
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lwmin = LMIN; |
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bwmin = Bl(LMIN); |
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} else { /* duplicate bottom bin */ |
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bwmin = bwmax - (bwmax-Bl(lwmin))*HISTRES/(HISTRES-1); |
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lwmin = Lb(bwmin); |
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} |
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/* (re)compute histogram */ |
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bwavg = 0.; |
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histot = 0.; |
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for (x = 0; x < HISTRES; x++) |
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bwhist[x] = 0.; |
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/* global average */ |
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if (!(what2do&DO_FIXHIST) || fixfrac < 1.-FTINY) |
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for (y = 0; y < fvyr; y++) |
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for (x = 0; x < fvxr; x++) { |
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l = plum(fovscan(y)[x]); |
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if (l < lwmin) continue; |
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if (l > lwmax) continue; |
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b = Bl(l); |
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bwavg += b; |
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w = what2do&DO_CWEIGHT ? centprob(x,y) : 1.; |
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bwhist[bwhi(b)] += w; |
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histot += w; |
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} |
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/* average fixation points */ |
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if (what2do&DO_FIXHIST && nfixations > 0) { |
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if (histot > FTINY) |
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w = fixfrac/(1.-fixfrac)*histot/nfixations; |
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else |
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w = 1.; |
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for (x = 0; x < nfixations; x++) { |
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l = plum(fovscan(fixlst[x][1])[fixlst[x][0]]); |
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if (l < lwmin) continue; |
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if (l > lwmax) continue; |
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b = Bl(l); |
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bwavg += b; |
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bwhist[bwhi(b)] += w; |
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histot += w; |
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} |
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} |
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bwavg /= histot; |
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if (lwmin > LMIN+FTINY) { /* add false samples at bottom */ |
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bwhist[1] *= 0.5; |
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bwhist[0] += bwhist[1]; |
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} |
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} |
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|
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|
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mkcumf() /* make cumulative distribution function */ |
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{ |
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register int i; |
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register double sum; |
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|
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mhistot = 0.; /* compute modified total */ |
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for (i = 0; i < HISTRES; i++) |
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mhistot += modhist[i]; |
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|
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sum = 0.; /* compute cumulative function */ |
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for (i = 0; i < HISTRES; i++) { |
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cumf[i] = sum/mhistot; |
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sum += modhist[i]; |
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} |
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cumf[HISTRES] = 1.; |
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} |
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|
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|
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double |
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cf(b) /* return cumulative function at b */ |
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double b; |
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{ |
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double x; |
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register int i; |
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|
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i = x = HISTRES*(b - bwmin)/(bwmax - bwmin); |
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x -= (double)i; |
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return(cumf[i]*(1.-x) + cumf[i+1]*x); |
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} |
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|
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|
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double |
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BLw(Lw) /* map world luminance to display brightness */ |
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double Lw; |
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{ |
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double b; |
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|
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if (Lw <= LMIN || (b = Bl(Lw)) <= bwmin+FTINY) |
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return(Bldmin); |
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if (b >= bwmax-FTINY) |
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return(Bldmax); |
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return(Bldmin + cf(b)*(Bldmax-Bldmin)); |
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} |
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|
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|
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double |
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htcontrs(La) /* human threshold contrast sensitivity, dL(La) */ |
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double La; |
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{ |
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double l10La, l10dL; |
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/* formula taken from Ferwerda et al. [SG96] */ |
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if (La < 1.148e-4) |
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return(1.38e-3); |
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l10La = log10(La); |
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if (l10La < -1.44) /* rod response regime */ |
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l10dL = pow(.405*l10La + 1.6, 2.18) - 2.86; |
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else if (l10La < -.0184) |
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l10dL = l10La - .395; |
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else if (l10La < 1.9) /* cone response regime */ |
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l10dL = pow(.249*l10La + .65, 2.7) - .72; |
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else |
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l10dL = l10La - 1.255; |
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|
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return(exp10(l10dL)); |
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} |
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|
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|
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double |
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clampf(Lw) /* derivative clamping function */ |
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double Lw; |
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{ |
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double bLw, ratio; |
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|
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bLw = BLw(Lw); /* apply current brightness map */ |
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ratio = what2do&DO_HSENS ? htcontrs(Lb(bLw))/htcontrs(Lw) : Lb(bLw)/Lw; |
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return(ratio/(Lb1(bLw)*(Bldmax-Bldmin)*Bl1(Lw))); |
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} |
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|
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|
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int |
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mkbrmap() /* make dynamic range map */ |
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{ |
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double T, b, s; |
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double ceiling, trimmings; |
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register int i; |
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/* copy initial histogram */ |
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bcopy((char *)bwhist, (char *)modhist, sizeof(modhist)); |
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s = (bwmax - bwmin)/HISTRES; |
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/* loop until satisfactory */ |
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do { |
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mkcumf(); /* sync brightness mapping */ |
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if (mhistot <= histot*CVRATIO) |
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return(-1); /* no compression needed! */ |
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T = mhistot * (bwmax - bwmin) / HISTRES; |
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trimmings = 0.; /* clip to envelope */ |
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for (i = 0, b = bwmin + .5*s; i < HISTRES; i++, b += s) { |
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ceiling = T*clampf(Lb(b)); |
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if (modhist[i] > ceiling) { |
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trimmings += modhist[i] - ceiling; |
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modhist[i] = ceiling; |
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} |
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} |
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} while (trimmings > histot*CVRATIO); |
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|
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return(0); /* we got it */ |
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} |
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|
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|
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scotscan(scan, xres) /* apply scotopic color sensitivity loss */ |
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COLOR *scan; |
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int xres; |
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{ |
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COLOR ctmp; |
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double incolor, b, Lw; |
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register int i; |
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|
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for (i = 0; i < xres; i++) { |
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Lw = plum(scan[i]); |
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if (Lw >= TopMesopic) |
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incolor = 1.; |
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else if (Lw <= BotMesopic) |
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incolor = 0.; |
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else |
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incolor = (Lw - BotMesopic) / |
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(TopMesopic - BotMesopic); |
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if (incolor < 1.-FTINY) { |
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b = (1.-incolor)*slum(scan[i])*inpexp/SWNORM; |
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if (lumf == rgblum) b /= WHTEFFICACY; |
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setcolor(ctmp, b, b, b); |
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if (incolor <= FTINY) |
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setcolor(scan[i], 0., 0., 0.); |
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else |
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scalecolor(scan[i], incolor); |
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addcolor(scan[i], ctmp); |
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} |
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} |
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} |
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|
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|
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mapscan(scan, xres) /* apply tone mapping operator to scanline */ |
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COLOR *scan; |
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int xres; |
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{ |
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double mult, Lw, b; |
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register int i; |
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|
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for (i = 0; i < xres; i++) { |
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Lw = plum(scan[i]); |
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if (Lw < LMIN) { |
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setcolor(scan[i], 0., 0., 0.); |
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continue; |
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} |
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b = BLw(Lw); |
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mult = (Lb(b) - ldmin)/(ldmax - ldmin) / (Lw*inpexp); |
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if (lumf == rgblum) mult *= WHTEFFICACY; |
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scalecolor(scan[i], mult); |
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} |
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} |
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|
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|
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putmapping(fp) /* put out mapping function */ |
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FILE *fp; |
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{ |
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double b, s; |
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register int i; |
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double wlum, sf, dlum; |
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|
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sf = scalef*inpexp; |
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if (lumf == cielum) sf *= WHTEFFICACY; |
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s = (bwmax - bwmin)/HISTRES; |
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for (i = 0, b = bwmin + .5*s; i < HISTRES; i++, b += s) { |
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wlum = Lb(b); |
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if (what2do&DO_LINEAR) { |
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dlum = sf*wlum; |
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if (dlum > ldmax) dlum = ldmax; |
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else if (dlum < ldmin) dlum = ldmin; |
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fprintf(fp, "%e %e\n", wlum, dlum); |
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} else |
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fprintf(fp, "%e %e\n", wlum, Lb(BLw(wlum))); |
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} |
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} |
