--- ray/src/px/pvalue.c	1997/01/08 07:43:49	2.10
+++ ray/src/px/pvalue.c	1998/10/27 09:08:27	2.13
@@ -43,6 +43,8 @@ int  header = 1;		/* do header? */
 
 long  skipbytes = 0;		/* skip bytes in input? */
 
+int  interleave = 1;		/* file is interleaved? */
+
 int  resolution = 1;		/* put/get resolution string? */
 
 int  original = 0;		/* convert to original values? */
@@ -119,6 +121,9 @@ char  **argv;
 			case 'r':		/* reverse conversion */
 				reverse = argv[i][0] == '-';
 				break;
+			case 'n':		/* non-interleaved RGB */
+				interleave = argv[i][0] == '+';
+				break;
 			case 'b':		/* brightness values */
 				putprim = argv[i][0] == '-' ? BRIGHT : ALL;
 				break;
@@ -205,8 +210,6 @@ unkopt:
 						progname, argv[i]);
 			quit(1);
 		}
-		if (skipbytes && fseek(fin, skipbytes, 0))
-			goto seekerr;
 		if (reverse && !brightonly && i == argc-3) {
 			if ((fin2 = fopen(argv[i+1], "r")) == NULL) {
 				fprintf(stderr, "%s: can't open file \"%s\"\n",
@@ -218,19 +221,26 @@ unkopt:
 						progname, argv[i+2]);
 				quit(1);
 			}
-			if (skipbytes && (fseek(fin2, skipbytes, 0) ||
-					fseek(fin3, skipbytes, 0)))
-				goto seekerr;
+			interleave = -1;
 		} else if (i != argc-1)
 			fin = NULL;
+		if (reverse && !brightonly && !interleave) {
+			fin2 = fopen(argv[i], "r");
+			fin3 = fopen(argv[i], "r");
+		}
+		if (skipbytes && (fseek(fin, skipbytes, 0) || (fin2 != NULL &&
+				(fseek(fin2, skipbytes, 0) ||
+				fseek(fin3, skipbytes, 0))))) {
+			fprintf(stderr, "%s: cannot skip %ld bytes on input\n",
+					progname, skipbytes);
+			quit(1);
+		}
 	}
 	if (fin == NULL) {
 		fprintf(stderr, "%s: bad # file arguments\n", progname);
 		quit(1);
 	}
 
-	set_io();
-
 	if (reverse) {
 #ifdef MSDOS
 		setmode(fileno(stdout), O_BINARY);
@@ -309,13 +319,10 @@ unkopt:
 	}
 
 	quit(0);
-seekerr:
-	fprintf(stderr, "%s: cannot skip %ld bytes on input\n",
-			progname, skipbytes);
-	quit(1);
 }
 
 
+int
 checkhead(line)				/* deal with line from header */
 char  *line;
 {
@@ -337,6 +344,7 @@ char  *line;
 		doexposure++;
 	} else if (header)
 		fputs(line, stdout);
+	return(0);
 }
 
 
@@ -346,6 +354,8 @@ pixtoval()				/* convert picture to values */
 	int  dogamma;
 	COLOR  lastc;
 	FLOAT  hv[2];
+	int  startprim, endprim;
+	long  startpos;
 	int  y;
 	register int  x;
 
@@ -355,39 +365,55 @@ pixtoval()				/* convert picture to values */
 		quit(1);
 	}
 	dogamma = gamcor < .95 || gamcor > 1.05;
-	setcolor(lastc, 0.0, 0.0, 0.0);
-	for (y = 0; y < numscans(&picres); y++) {
-		if (freadscan(scanln, scanlen(&picres), fin) < 0) {
-			fprintf(stderr, "%s: read error\n", progname);
+	if (putprim == ALL && !interleave) {
+		startprim = RED; endprim = BLU;
+		startpos = ftell(fin);
+	} else {
+		startprim = putprim; endprim = putprim;
+	}
+	for (putprim = startprim; putprim <= endprim; putprim++) {
+		if (putprim != startprim && fseek(fin, startpos, 0)) {
+			fprintf(stderr, "%s: seek error on input file\n",
+					progname);
 			quit(1);
 		}
-		for (x = 0; x < scanlen(&picres); x++) {
-			if (uniq)
-				if (	colval(scanln[x],RED) ==
-						colval(lastc,RED) &&
-					colval(scanln[x],GRN) ==
-						colval(lastc,GRN) &&
-					colval(scanln[x],BLU) ==
-						colval(lastc,BLU)	)
-					continue;
-				else
-					copycolor(lastc, scanln[x]);
-			if (doexposure)
-				multcolor(scanln[x], exposure);
-			if (dogamma)
-				setcolor(scanln[x],
-				pow(colval(scanln[x],RED), 1.0/gamcor),
-				pow(colval(scanln[x],GRN), 1.0/gamcor),
-				pow(colval(scanln[x],BLU), 1.0/gamcor));
-			if (!dataonly) {
-				pix2loc(hv, &picres, x, y);
-				printf("%7d %7d ", (int)(hv[0]*picres.xr),
-						(int)(hv[1]*picres.yr));
-			}
-			if ((*putval)(scanln[x], stdout) < 0) {
-				fprintf(stderr, "%s: write error\n", progname);
+		set_io();
+		setcolor(lastc, 0.0, 0.0, 0.0);
+		for (y = 0; y < numscans(&picres); y++) {
+			if (freadscan(scanln, scanlen(&picres), fin) < 0) {
+				fprintf(stderr, "%s: read error\n", progname);
 				quit(1);
 			}
+			for (x = 0; x < scanlen(&picres); x++) {
+				if (uniq)
+					if (	colval(scanln[x],RED) ==
+							colval(lastc,RED) &&
+						colval(scanln[x],GRN) ==
+							colval(lastc,GRN) &&
+						colval(scanln[x],BLU) ==
+							colval(lastc,BLU)	)
+						continue;
+					else
+						copycolor(lastc, scanln[x]);
+				if (doexposure)
+					multcolor(scanln[x], exposure);
+				if (dogamma)
+					setcolor(scanln[x],
+					pow(colval(scanln[x],RED), 1.0/gamcor),
+					pow(colval(scanln[x],GRN), 1.0/gamcor),
+					pow(colval(scanln[x],BLU), 1.0/gamcor));
+				if (!dataonly) {
+					pix2loc(hv, &picres, x, y);
+					printf("%7d %7d ",
+							(int)(hv[0]*picres.xr),
+							(int)(hv[1]*picres.yr));
+				}
+				if ((*putval)(scanln[x]) < 0) {
+					fprintf(stderr, "%s: write error\n",
+							progname);
+					quit(1);
+				}
+			}
 		}
 	}
 	free((char *)scanln);
@@ -407,6 +433,7 @@ valtopix()			/* convert values to a pixel file */
 		quit(1);
 	}
 	dogamma = gamcor < .95 || gamcor > 1.05;
+	set_io();
 	for (y = 0; y < numscans(&picres); y++) {
 		for (x = 0; x < scanlen(&picres); x++) {
 			if (!dataonly) {
@@ -416,7 +443,7 @@ valtopix()			/* convert values to a pixel file */
 					fscanf(fin3, "%*d %*d");
 				}
 			}
-			if ((*getval)(scanln[x], fin, fin2, fin3) < 0) {
+			if ((*getval)(scanln[x]) < 0) {
 				fprintf(stderr, "%s: read error\n", progname);
 				quit(1);
 			}
@@ -444,19 +471,18 @@ int  code;
 }
 
 
-getcascii(col, f1, f2, f3)	/* get an ascii color value from stream(s) */
+getcascii(col)		/* get an ascii color value from stream(s) */
 COLOR  col;
-FILE  *f1, *f2, *f3;
 {
 	double	vd[3];
 
-	if (f2 == NULL) {
-		if (fscanf(f1, "%lf %lf %lf", &vd[0], &vd[1], &vd[2]) != 3)
+	if (fin2 == NULL) {
+		if (fscanf(fin, "%lf %lf %lf", &vd[0], &vd[1], &vd[2]) != 3)
 			return(-1);
 	} else {
-		if (fscanf(f1, "%lf", &vd[0]) != 1 ||
-				fscanf(f2, "%lf", &vd[1]) != 1 ||
-				fscanf(f3, "%lf", &vd[2]) != 1)
+		if (fscanf(fin, "%lf", &vd[0]) != 1 ||
+				fscanf(fin2, "%lf", &vd[1]) != 1 ||
+				fscanf(fin3, "%lf", &vd[2]) != 1)
 			return(-1);
 	}
 	setcolor(col, vd[rord[RED]], vd[rord[GRN]], vd[rord[BLU]]);
@@ -464,19 +490,18 @@ FILE  *f1, *f2, *f3;
 }
 
 
-getcdouble(col, f1, f2, f3)	/* get a double color value from stream(s) */
+getcdouble(col)		/* get a double color value from stream(s) */
 COLOR  col;
-FILE  *f1, *f2, *f3;
 {
 	double	vd[3];
 
-	if (f2 == NULL) {
-		if (fread((char *)vd, sizeof(double), 3, f1) != 3)
+	if (fin2 == NULL) {
+		if (fread((char *)vd, sizeof(double), 3, fin) != 3)
 			return(-1);
 	} else {
-		if (fread((char *)vd, sizeof(double), 1, f1) != 1 ||
-			fread((char *)(vd+1), sizeof(double), 1, f2) != 1 ||
-			fread((char *)(vd+2), sizeof(double), 1, f3) != 1)
+		if (fread((char *)vd, sizeof(double), 1, fin) != 1 ||
+			fread((char *)(vd+1), sizeof(double), 1, fin2) != 1 ||
+			fread((char *)(vd+2), sizeof(double), 1, fin3) != 1)
 			return(-1);
 	}
 	setcolor(col, vd[rord[RED]], vd[rord[GRN]], vd[rord[BLU]]);
@@ -484,19 +509,18 @@ FILE  *f1, *f2, *f3;
 }
 
 
-getcfloat(col, f1, f2, f3)	/* get a float color value from stream(s) */
+getcfloat(col)		/* get a float color value from stream(s) */
 COLOR  col;
-FILE  *f1, *f2, *f3;
 {
 	float  vf[3];
 
-	if (f2 == NULL) {
-		if (fread((char *)vf, sizeof(float), 3, f1) != 3)
+	if (fin2 == NULL) {
+		if (fread((char *)vf, sizeof(float), 3, fin) != 3)
 			return(-1);
 	} else {
-		if (fread((char *)vf, sizeof(float), 1, f1) != 1 ||
-			fread((char *)(vf+1), sizeof(float), 1, f2) != 1 ||
-			fread((char *)(vf+2), sizeof(float), 1, f3) != 1)
+		if (fread((char *)vf, sizeof(float), 1, fin) != 1 ||
+			fread((char *)(vf+1), sizeof(float), 1, fin2) != 1 ||
+			fread((char *)(vf+2), sizeof(float), 1, fin3) != 1)
 			return(-1);
 	}
 	setcolor(col, vf[rord[RED]], vf[rord[GRN]], vf[rord[BLU]]);
@@ -504,19 +528,18 @@ FILE  *f1, *f2, *f3;
 }
 
 
-getcint(col, f1, f2, f3)	/* get an int color value from stream(s) */
+getcint(col)		/* get an int color value from stream(s) */
 COLOR  col;
-FILE  *f1, *f2, *f3;
 {
 	int  vi[3];
 
-	if (f2 == NULL) {
-		if (fscanf(f1, "%d %d %d", &vi[0], &vi[1], &vi[2]) != 3)
+	if (fin2 == NULL) {
+		if (fscanf(fin, "%d %d %d", &vi[0], &vi[1], &vi[2]) != 3)
 			return(-1);
 	} else {
-		if (fscanf(f1, "%d", &vi[0]) != 1 ||
-				fscanf(f2, "%d", &vi[1]) != 1 ||
-				fscanf(f3, "%d", &vi[2]) != 1)
+		if (fscanf(fin, "%d", &vi[0]) != 1 ||
+				fscanf(fin2, "%d", &vi[1]) != 1 ||
+				fscanf(fin3, "%d", &vi[2]) != 1)
 			return(-1);
 	}
 	setcolor(col, (vi[rord[RED]]+.5)/256.,
@@ -525,19 +548,18 @@ FILE  *f1, *f2, *f3;
 }
 
 
-getcbyte(col, f1, f2, f3)	/* get a byte color value from stream(s) */
+getcbyte(col)		/* get a byte color value from stream(s) */
 COLOR  col;
-FILE  *f1, *f2, *f3;
 {
 	BYTE  vb[3];
 
-	if (f2 == NULL) {
-		if (fread((char *)vb, sizeof(BYTE), 3, f1) != 3)
+	if (fin2 == NULL) {
+		if (fread((char *)vb, sizeof(BYTE), 3, fin) != 3)
 			return(-1);
 	} else {
-		if (fread((char *)vb, sizeof(BYTE), 1, f1) != 1 ||
-			fread((char *)(vb+1), sizeof(BYTE), 1, f2) != 1 ||
-			fread((char *)(vb+2), sizeof(BYTE), 1, f3) != 1)
+		if (fread((char *)vb, sizeof(BYTE), 1, fin) != 1 ||
+			fread((char *)(vb+1), sizeof(BYTE), 1, fin2) != 1 ||
+			fread((char *)(vb+2), sizeof(BYTE), 1, fin3) != 1)
 			return(-1);
 	}
 	setcolor(col, (vb[rord[RED]]+.5)/256.,
@@ -546,53 +568,49 @@ FILE  *f1, *f2, *f3;
 }
 
 
-getbascii(col, fp)		/* get an ascii brightness value from fp */
+getbascii(col)		/* get an ascii brightness value from fin */
 COLOR  col;
-FILE  *fp;
 {
 	double	vd;
 
-	if (fscanf(fp, "%lf", &vd) != 1)
+	if (fscanf(fin, "%lf", &vd) != 1)
 		return(-1);
 	setcolor(col, vd, vd, vd);
 	return(0);
 }
 
 
-getbdouble(col, fp)		/* get a double brightness value from fp */
+getbdouble(col)		/* get a double brightness value from fin */
 COLOR  col;
-FILE  *fp;
 {
 	double	vd;
 
-	if (fread((char *)&vd, sizeof(double), 1, fp) != 1)
+	if (fread((char *)&vd, sizeof(double), 1, fin) != 1)
 		return(-1);
 	setcolor(col, vd, vd, vd);
 	return(0);
 }
 
 
-getbfloat(col, fp)		/* get a float brightness value from fp */
+getbfloat(col)		/* get a float brightness value from fin */
 COLOR  col;
-FILE  *fp;
 {
 	float  vf;
 
-	if (fread((char *)&vf, sizeof(float), 1, fp) != 1)
+	if (fread((char *)&vf, sizeof(float), 1, fin) != 1)
 		return(-1);
 	setcolor(col, vf, vf, vf);
 	return(0);
 }
 
 
-getbint(col, fp)		/* get an int brightness value from fp */
+getbint(col)		/* get an int brightness value from fin */
 COLOR  col;
-FILE  *fp;
 {
 	int  vi;
 	double	d;
 
-	if (fscanf(fp, "%d", &vi) != 1)
+	if (fscanf(fin, "%d", &vi) != 1)
 		return(-1);
 	d = (vi+.5)/256.;
 	setcolor(col, d, d, d);
@@ -600,14 +618,13 @@ FILE  *fp;
 }
 
 
-getbbyte(col, fp)		/* get a byte brightness value from fp */
+getbbyte(col)		/* get a byte brightness value from fin */
 COLOR  col;
-FILE  *fp;
 {
 	BYTE  vb;
 	double	d;
 
-	if (fread((char *)&vb, sizeof(BYTE), 1, fp) != 1)
+	if (fread((char *)&vb, sizeof(BYTE), 1, fin) != 1)
 		return(-1);
 	d = (vb+.5)/256.;
 	setcolor(col, d, d, d);
@@ -615,65 +632,60 @@ FILE  *fp;
 }
 
 
-putcascii(col, fp)			/* put an ascii color to fp */
+putcascii(col)			/* put an ascii color to stdout */
 COLOR  col;
-FILE  *fp;
 {
-	fprintf(fp, "%15.3e %15.3e %15.3e\n",
+	fprintf(stdout, "%15.3e %15.3e %15.3e\n",
 			colval(col,ord[0]),
 			colval(col,ord[1]),
 			colval(col,ord[2]));
 
-	return(ferror(fp) ? -1 : 0);
+	return(ferror(stdout) ? -1 : 0);
 }
 
 
-putcfloat(col, fp)			/* put a float color to fp */
+putcfloat(col)			/* put a float color to stdout */
 COLOR  col;
-FILE  *fp;
 {
 	float  vf[3];
 
 	vf[0] = colval(col,ord[0]);
 	vf[1] = colval(col,ord[1]);
 	vf[2] = colval(col,ord[2]);
-	fwrite((char *)vf, sizeof(float), 3, fp);
+	fwrite((char *)vf, sizeof(float), 3, stdout);
 
-	return(ferror(fp) ? -1 : 0);
+	return(ferror(stdout) ? -1 : 0);
 }
 
 
-putcdouble(col, fp)			/* put a double color to fp */
+putcdouble(col)			/* put a double color to stdout */
 COLOR  col;
-FILE  *fp;
 {
 	double	vd[3];
 
 	vd[0] = colval(col,ord[0]);
 	vd[1] = colval(col,ord[1]);
 	vd[2] = colval(col,ord[2]);
-	fwrite((char *)vd, sizeof(double), 3, fp);
+	fwrite((char *)vd, sizeof(double), 3, stdout);
 
-	return(ferror(fp) ? -1 : 0);
+	return(ferror(stdout) ? -1 : 0);
 }
 
 
-putcint(col, fp)			/* put an int color to fp */
+putcint(col)			/* put an int color to stdout */
 COLOR  col;
-FILE  *fp;
 {
-	fprintf(fp, "%d %d %d\n",
+	fprintf(stdout, "%d %d %d\n",
 			(int)(colval(col,ord[0])*256.),
 			(int)(colval(col,ord[1])*256.),
 			(int)(colval(col,ord[2])*256.));
 
-	return(ferror(fp) ? -1 : 0);
+	return(ferror(stdout) ? -1 : 0);
 }
 
 
-putcbyte(col, fp)			/* put a byte color to fp */
+putcbyte(col)			/* put a byte color to stdout */
 COLOR  col;
-FILE  *fp;
 {
 	register int  i;
 	BYTE  vb[3];
@@ -684,131 +696,121 @@ FILE  *fp;
 	vb[1] = min(i,255);
 	i = colval(col,ord[2])*256.;
 	vb[2] = min(i,255);
-	fwrite((char *)vb, sizeof(BYTE), 3, fp);
+	fwrite((char *)vb, sizeof(BYTE), 3, stdout);
 
-	return(ferror(fp) ? -1 : 0);
+	return(ferror(stdout) ? -1 : 0);
 }
 
 
-putbascii(col, fp)			/* put an ascii brightness to fp */
+putbascii(col)			/* put an ascii brightness to stdout */
 COLOR  col;
-FILE  *fp;
 {
-	fprintf(fp, "%15.3e\n", bright(col));
+	fprintf(stdout, "%15.3e\n", bright(col));
 
-	return(ferror(fp) ? -1 : 0);
+	return(ferror(stdout) ? -1 : 0);
 }
 
 
-putbfloat(col, fp)			/* put a float brightness to fp */
+putbfloat(col)			/* put a float brightness to stdout */
 COLOR  col;
-FILE  *fp;
 {
 	float  vf;
 
 	vf = bright(col);
-	fwrite((char *)&vf, sizeof(float), 1, fp);
+	fwrite((char *)&vf, sizeof(float), 1, stdout);
 
-	return(ferror(fp) ? -1 : 0);
+	return(ferror(stdout) ? -1 : 0);
 }
 
 
-putbdouble(col, fp)			/* put a double brightness to fp */
+putbdouble(col)			/* put a double brightness to stdout */
 COLOR  col;
-FILE  *fp;
 {
 	double	vd;
 
 	vd = bright(col);
-	fwrite((char *)&vd, sizeof(double), 1, fp);
+	fwrite((char *)&vd, sizeof(double), 1, stdout);
 
-	return(ferror(fp) ? -1 : 0);
+	return(ferror(stdout) ? -1 : 0);
 }
 
 
-putbint(col, fp)			/* put an int brightness to fp */
+putbint(col)			/* put an int brightness to stdout */
 COLOR  col;
-FILE  *fp;
 {
-	fprintf(fp, "%d\n", (int)(bright(col)*256.));
+	fprintf(stdout, "%d\n", (int)(bright(col)*256.));
 
-	return(ferror(fp) ? -1 : 0);
+	return(ferror(stdout) ? -1 : 0);
 }
 
 
-putbbyte(col, fp)			/* put a byte brightness to fp */
+putbbyte(col)			/* put a byte brightness to stdout */
 COLOR  col;
-FILE  *fp;
 {
 	register int  i;
 	BYTE  vb;
 
 	i = bright(col)*256.;
 	vb = min(i,255);
-	fwrite((char *)&vb, sizeof(BYTE), 1, fp);
+	fwrite((char *)&vb, sizeof(BYTE), 1, stdout);
 
-	return(ferror(fp) ? -1 : 0);
+	return(ferror(stdout) ? -1 : 0);
 }
 
 
-putpascii(col, fp)			/* put an ascii primary to fp */
+putpascii(col)			/* put an ascii primary to stdout */
 COLOR  col;
-FILE  *fp;
 {
-	fprintf(fp, "%15.3e\n", colval(col,putprim));
+	fprintf(stdout, "%15.3e\n", colval(col,putprim));
 
-	return(ferror(fp) ? -1 : 0);
+	return(ferror(stdout) ? -1 : 0);
 }
 
 
-putpfloat(col, fp)			/* put a float primary to fp */
+putpfloat(col)			/* put a float primary to stdout */
 COLOR  col;
-FILE  *fp;
 {
 	float  vf;
 
 	vf = colval(col,putprim);
-	fwrite((char *)&vf, sizeof(float), 1, fp);
+	fwrite((char *)&vf, sizeof(float), 1, stdout);
 
-	return(ferror(fp) ? -1 : 0);
+	return(ferror(stdout) ? -1 : 0);
 }
 
 
-putpdouble(col, fp)			/* put a double primary to fp */
+putpdouble(col)			/* put a double primary to stdout */
 COLOR  col;
-FILE  *fp;
 {
 	double	vd;
 
 	vd = colval(col,putprim);
-	fwrite((char *)&vd, sizeof(double), 1, fp);
+	fwrite((char *)&vd, sizeof(double), 1, stdout);
 
-	return(ferror(fp) ? -1 : 0);
+	return(ferror(stdout) ? -1 : 0);
 }
 
 
-putpint(col, fp)			/* put an int primary to fp */
+putpint(col)			/* put an int primary to stdout */
 COLOR  col;
-FILE  *fp;
 {
-	fprintf(fp, "%d\n", (int)(colval(col,putprim)*256.));
+	fprintf(stdout, "%d\n", (int)(colval(col,putprim)*256.));
 
-	return(ferror(fp) ? -1 : 0);
+	return(ferror(stdout) ? -1 : 0);
 }
 
 
-putpbyte(col, fp)			/* put a byte primary to fp */
+putpbyte(col)			/* put a byte primary to stdout */
 COLOR  col;
-FILE  *fp;
 {
 	register int  i;
 	BYTE  vb;
 
 	i = colval(col,putprim)*256.;
 	vb = min(i,255);
-	fwrite((char *)&vb, sizeof(BYTE), 1, fp);
+	fwrite((char *)&vb, sizeof(BYTE), 1, stdout);
 
-	return(ferror(fp) ? -1 : 0);
+	return(ferror(stdout) ? -1 : 0);
 }
 
 
@@ -825,6 +827,12 @@ set_io()			/* set put and get functions */
 		} else {
 			getval = getcascii;
 			putval = putcascii;
+			if (reverse && !interleave) {
+				fprintf(stderr,
+				"%s: ASCII input files must be interleaved\n",
+						progname);
+				quit(1);
+			}
 		}
 		return;
 	case 'f':					/* binary float */
@@ -837,6 +845,16 @@ set_io()			/* set put and get functions */
 		} else {
 			getval = getcfloat;
 			putval = putcfloat;
+			if (reverse && !interleave) {
+				if (fin2 == NULL)
+					goto namerr;
+				if (fseek(fin2,
+				(long)sizeof(float)*picres.xr*picres.yr, 1))
+					goto seekerr;
+				if (fseek(fin3,
+				(long)sizeof(float)*2*picres.xr*picres.yr, 1))
+					goto seekerr;
+			}
 		}
 		return;
 	case 'd':					/* binary double */
@@ -849,6 +867,16 @@ set_io()			/* set put and get functions */
 		} else {
 			getval = getcdouble;
 			putval = putcdouble;
+			if (reverse && !interleave) {
+				if (fin2 == NULL)
+					goto namerr;
+				if (fseek(fin2,
+				(long)sizeof(double)*picres.xr*picres.yr, 1))
+					goto seekerr;
+				if (fseek(fin3,
+				(long)sizeof(double)*2*picres.xr*picres.yr, 1))
+					goto seekerr;
+			}
 		}
 		return;
 	case 'i':					/* integer */
@@ -861,6 +889,12 @@ set_io()			/* set put and get functions */
 		} else {
 			getval = getcint;
 			putval = putcint;
+			if (reverse && !interleave) {
+				fprintf(stderr,
+				"%s: integer input files must be interleaved\n",
+						progname);
+				quit(1);
+			}
 		}
 		return;
 	case 'b':					/* byte */
@@ -873,7 +907,28 @@ set_io()			/* set put and get functions */
 		} else {
 			getval = getcbyte;
 			putval = putcbyte;
+			if (reverse && !interleave) {
+				if (fin2 == NULL)
+					goto namerr;
+				if (fseek(fin2,
+				(long)sizeof(BYTE)*picres.xr*picres.yr, 1))
+					goto seekerr;
+				if (fseek(fin3,
+				(long)sizeof(BYTE)*2*picres.xr*picres.yr, 1))
+					goto seekerr;
+			}
 		}
 		return;
 	}
+badopt:
+	fprintf(stderr, "%s: botched file type\n", progname);
+	quit(1);
+namerr:
+	fprintf(stderr, "%s: non-interleaved file(s) must be named\n",
+			progname);
+	quit(1);
+seekerr:
+	fprintf(stderr, "%s: cannot seek on interleaved input file\n",
+			progname);
+	quit(1);
 }