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#include "pcond.h" |
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#define CVRATIO 0.025 /* fraction of pixels allowed > env. */ |
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#define CVRATIO 0.025 /* fraction of samples allowed > env. */ |
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#define exp10(x) exp(2.302585093*(x)) |
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int modhist[HISTRES]; /* modified histogram */ |
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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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mkcumf() /* make cumulative distribution function */ |
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{ |
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register int i; |
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register long sum; |
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register double sum; |
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cumf[0] = 0.; |
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sum = modhist[0]; |
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for (i = 1; i < HISTRES; i++) { |
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cumf[i] = (double)sum/histot; |
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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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int |
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mkbrmap() /* make dynamic range map */ |
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{ |
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int hdiffs[HISTRES], above, below; |
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double T, b, s; |
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int maxd, maxi, sd; |
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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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for (i = 0; i < HISTRES; i++) |
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modhist[i] = bwhist[i]; |
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T = histot * (bwmax - bwmin) / HISTRES; |
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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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for ( ; ; ) { |
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mkcumf(); /* sync brightness mapping */ |
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above = below = 0; /* compute visibility overflow */ |
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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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hdiffs[i] = modhist[i] - (int)(T*clampf(Lb(b)) + .5); |
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if (hdiffs[i] > 0) above += hdiffs[i]; |
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else below -= hdiffs[i]; |
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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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if (above <= histot*CVRATIO) |
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break; /* close enough */ |
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if (above-below >= 0) |
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return(-1); /* Houston, we have a problem.... */ |
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/* original looped here as well (BEGIN_L2) */ |
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maxd = 0; /* find largest overvis */ |
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for (i = 0; i < HISTRES; i++) |
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if (hdiffs[i] > maxd) |
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maxd = hdiffs[maxi=i]; |
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/* broke loop here when (maxd == 0) (BREAK_L2) */ |
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for (sd = shiftdir((maxi+.5)/HISTRES*(bwmax-bwmin)+bwmin); |
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hdiffs[maxi] == maxd; sd = -sd) |
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for (i = maxi+sd; i >= 0 & i < HISTRES; i += sd) |
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if (hdiffs[i] < 0) { |
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if (hdiffs[i] <= -maxd) { |
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modhist[i] += maxd; |
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modhist[maxi] -= maxd; |
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hdiffs[i] += maxd; |
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hdiffs[maxi] = 0; |
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} else { |
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modhist[maxi] += hdiffs[i]; |
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modhist[i] -= hdiffs[i]; |
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hdiffs[maxi] += hdiffs[i]; |
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hdiffs[i] = 0; |
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} |
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break; |
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} |
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/* (END_L2) */ |
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} |
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return(0); |
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} while (trimmings > histot*CVRATIO); |
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return(0); /* we got it */ |
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} |
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fprintf(fp, "%e %e\n", wlum, Lb(BLw(wlum))); |
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} |
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} |
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#ifdef DEBUG |
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doplots() /* generate debugging plots */ |
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{ |
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double T, b, s; |
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FILE *fp; |
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char fname[128]; |
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register int i; |
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|
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T = histot * (bwmax - bwmin) / HISTRES; |
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s = (bwmax - bwmin)/HISTRES; |
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|
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sprintf(fname, "%s_hist.plt", infn); |
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if ((fp = fopen(fname, "w")) == NULL) |
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syserror(fname); |
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fputs("include=curve.plt\n", fp); |
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fputs("title=\"Brightness Frequency Distribution\"\n", fp); |
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fprintf(fp, "subtitle=%s\n", infn); |
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fputs("ymin=0\n", fp); |
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fputs("xlabel=\"Perceptual Brightness B(Lw)\"\n", fp); |
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fputs("ylabel=\"Frequency Count\"\n", fp); |
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fputs("Alabel=\"Histogram\"\n", fp); |
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fputs("Alintype=0\n", fp); |
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fputs("Blabel=\"Envelope\"\n", fp); |
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fputs("Bsymsize=0\n", fp); |
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fputs("Adata=\n", fp); |
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for (i = 0, b = bwmin + .5*s; i < HISTRES; i++, b += s) |
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fprintf(fp, "\t%f %d\n", b, modhist[i]); |
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fputs(";\nBdata=\n", fp); |
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for (i = 0, b = bwmin + .5*s; i < HISTRES; i++, b += s) |
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fprintf(fp, "\t%f %f\n", b, T*clampf(Lb(b))); |
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fputs(";\n", fp); |
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fclose(fp); |
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} |
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#endif |