--- ray/src/px/macbethcal.c	1997/01/31 15:56:17	2.13
+++ ray/src/px/macbethcal.c	2024/02/22 02:07:40	2.29
@@ -1,22 +1,25 @@
-/* Copyright (c) 1997 Regents of the University of California */
-
 #ifndef lint
-static char SCCSid[] = "$SunId$ LBL";
+static const char	RCSid[] = "$Id: macbethcal.c,v 2.29 2024/02/22 02:07:40 greg Exp $";
 #endif
-
 /*
  * Calibrate a scanned MacBeth Color Checker Chart
  *
- * Produce a .cal file suitable for use with pcomb.
+ * Produce a .cal file suitable for use with pcomb,
+ * or .cwp file suitable for use with pcwarp.
+ *
+ * Warping code depends on conformance of COLOR and W3VEC types.
  */
 
-#include <stdio.h>
-#ifdef MSDOS
-#include <fcntl.h>
-#endif
+#include <math.h>
+
+#include "platform.h"
+#include "paths.h"
+#include "rtio.h"
 #include "color.h"
 #include "resolu.h"
 #include "pmap.h"
+#include "warp3d.h"
+#include "mx3.h"
 
 				/* MacBeth colors */
 #define	DarkSkin	0
@@ -43,33 +46,33 @@ static char SCCSid[] = "$SunId$ LBL";
 #define	Neutral5	21
 #define	Neutral35	22
 #define	Black		23
-				/* computed from 5nm spectral measurements */
+				/* computed from 10nm spectral measurements */
 				/* CIE 1931 2 degree obs, equal-energy white */
 float	mbxyY[24][3] = {
-		{0.462, 0.3769, 0.0932961},	/* DarkSkin */
-		{0.4108, 0.3542, 0.410348},	/* LightSkin */
-		{0.2626, 0.267, 0.181554},	/* BlueSky */
-		{0.36, 0.4689, 0.108447},	/* Foliage */
-		{0.2977, 0.2602, 0.248407},	/* BlueFlower */
-		{0.2719, 0.3485, 0.401156},	/* BluishGreen */
-		{0.52, 0.4197, 0.357899},	/* Orange */
-		{0.229, 0.1866, 0.103911},	/* PurplishBlue */
-		{0.4909, 0.3262, 0.242615},	/* ModerateRed */
-		{0.3361, 0.2249, 0.0600102},	/* Purple */
-		{0.3855, 0.4874, 0.42963},	/* YellowGreen */
-		{0.4853, 0.4457, 0.476343},	/* OrangeYellow */
-		{0.2026, 0.1369, 0.0529249},	/* Blue */
-		{0.3007, 0.4822, 0.221226},	/* Green */
-		{0.5805, 0.3238, 0.162167},	/* Red */
-		{0.4617, 0.472, 0.64909},	/* Yellow */
-		{0.4178, 0.2625, 0.233662},	/* Magenta */
-		{0.2038, 0.2508, 0.167275},	/* Cyan */
-		{0.3358, 0.337, 0.916877},	/* White */
-		{0.3338, 0.3348, 0.604678},	/* Neutral.8 */
-		{0.3333, 0.3349, 0.364566},	/* Neutral.65 */
-		{0.3353, 0.3359, 0.200238},	/* Neutral.5 */
-		{0.3363, 0.336, 0.0878721},	/* Neutral.35 */
-		{0.3346, 0.3349, 0.0308383}	/* Black */
+		{0.421236, 0.361196, 0.103392},		/* DarkSkin */
+		{0.40868, 0.358157, 0.352867},		/* LightSkin */
+		{0.265063, 0.271424, 0.185124},		/* BlueSky */
+		{0.362851, 0.43055, 0.132625},		/* Foliage */
+		{0.28888, 0.260851, 0.233138},		/* BlueFlower */
+		{0.277642, 0.365326, 0.416443},		/* BluishGreen */
+		{0.524965, 0.40068, 0.312039},		/* Orange */
+		{0.225018, 0.190392, 0.114999},		/* PurplishBlue */
+		{0.487199, 0.315372, 0.198616},		/* ModerateRed */
+		{0.314245, 0.227231, 0.0646047},	/* Purple */
+		{0.396202, 0.489732, 0.440724},		/* YellowGreen */
+		{0.493297, 0.435299, 0.43444},		/* OrangeYellow */
+		{0.198191, 0.149265, 0.0588122},	/* Blue */
+		{0.322838, 0.487601, 0.229258},		/* Green */
+		{0.561833, 0.321165, 0.126978},		/* Red */
+		{0.468113, 0.467021, 0.605289},		/* Yellow */
+		{0.397128, 0.248535, 0.201761},		/* Magenta */
+		{0.209552, 0.276256, 0.190917},		/* Cyan */
+		{0.337219, 0.339042, 0.912482},		/* White */
+		{0.333283, 0.335077, 0.588297},		/* Neutral.8 */
+		{0.332747, 0.334371, 0.3594},		/* Neutral.65 */
+		{0.331925, 0.334202, 0.19114},		/* Neutral.5 */
+		{0.330408, 0.332615, 0.0892964},	/* Neutral.35 */
+		{0.331841, 0.331405, 0.0319541},	/* Black */
 	};
 
 COLOR	mbRGB[24];		/* MacBeth RGB values */
@@ -95,7 +98,13 @@ short	mbneu[NMBNEU] = {Black,Neutral35,Neutral5,Neutra
 #define  RG_ORIG	02	/* original color region */
 #define  RG_CORR	04	/* corrected color region */
 
+#ifndef  DISPCOM
+#define  DISPCOM	"ximage -e auto -op \"%s\""
+#endif
+
 int	scanning = 1;		/* scanned input (or recorded output)? */
+double	irrad = 1.0;		/* irradiance multiplication factor */
+int	rawmap = 0;		/* put out raw color mapping? */
 
 int	xmax, ymax;		/* input image dimensions */
 int	bounds[4][2];		/* image coordinates of chart corners */
@@ -109,15 +118,34 @@ COLOR	bramp[NMBNEU][2];	/* brightness ramp (per primar
 COLORMAT	solmat;		/* color mapping matrix */
 COLOR	colmin, colmax;		/* gamut limits */
 
+WARP3D	*wcor = NULL;		/* color space warp */
+
 FILE	*debugfp = NULL;	/* debug output picture */
 char	*progname;
 
-extern char	*malloc();
+static void init(void);
+static int chartndx(int	x, int y, int	*np);
+static void getpicture(void);
+static void getcolors(void);
+static void bresp(COLOR	y, COLOR	x);
+static void compute(void);
+static void putmapping(void);
+static void compsoln(COLOR	cin[], COLOR	cout[], int	n);
+static void cwarp(void);
+static int cvtcolor(COLOR	cout, COLOR	cin);
+static int cresp(COLOR	cout, COLOR	cin);
+static void xyY2RGB(COLOR	rgbout, float	xyYin[3]);
+static void picdebug(void);
+static void clrdebug(void);
+static void getpos(char	*name, int	bnds[2], FILE	*fp);
+static void pickchartpos(char	*pfn);
 
 
-main(argc, argv)
-int	argc;
-char	**argv;
+int
+main(
+	int	argc,
+	char	**argv
+)
 {
 	int	i;
 
@@ -132,9 +160,7 @@ char	**argv;
 				perror(argv[i]);
 				exit(1);
 			}
-#ifdef MSDOS
-			setmode(fileno(debugfp), O_BINARY);
-#endif
+			SET_FILE_BINARY(debugfp);
 			newheader("RADIANCE", debugfp);		/* start */
 			printargs(argc, argv, debugfp);		/* header */
 			break;
@@ -151,6 +177,18 @@ char	**argv;
 			bounds[3][1] = atoi(argv[++i]);
 			scanning = 2;
 			break;
+		case 'P':				/* pick position */
+			scanning = 3;
+			break;
+		case 'i':				/* irradiance factor */
+			i++;
+			if (badarg(argc-i, argv+i, "f"))
+				goto userr;
+			irrad = atof(argv[i]);
+			break;
+		case 'm':				/* raw map output */
+			rawmap = 1;
+			break;
 		case 'c':				/* color input */
 			scanning = 0;
 			break;
@@ -167,14 +205,18 @@ char	**argv;
 		exit(1);
 	}
 	if (scanning) {			/* load input picture header */
-#ifdef MSDOS
-		setmode(fileno(stdin), O_BINARY);
-#endif
+		SET_FILE_BINARY(stdin);
 		if (checkheader(stdin, COLRFMT, NULL) < 0 ||
 				fgetresolu(&xmax, &ymax, stdin) < 0) {
 			fprintf(stderr, "%s: bad input picture\n", progname);
 			exit(1);
 		}
+		if (scanning == 3) {
+			if (i >= argc)
+				goto userr;
+			pickchartpos(argv[i]);
+			scanning = 2;
+		}
 	} else {			/* else set default xmax and ymax */
 		xmax = 512;
 		ymax = 2*512/3;
@@ -191,36 +233,57 @@ char	**argv;
 	else
 		getcolors();
 	compute();			/* compute color mapping */
-					/* print comment */
-	printf("{\n\tColor correction file computed by:\n\t\t");
-	printargs(argc, argv, stdout);
-	printf("\n\tUsage: pcomb -f %s uncorrected.pic > corrected.pic\n",
-			i+1 < argc ? argv[i+1] : "{this_file}");
-	if (!scanning)
-		printf("\t   Or: pcond [options] -f %s orig.pic > output.pic\n",
+	if (rawmap) {			/* print out raw correspondence */
+		int	j;
+
+		printf("# Color correspondence produced by:\n#\t\t");
+		printargs(argc, argv, stdout);
+		printf("#\tUsage: pcwarp %s uncorrected.hdr > corrected.hdr\n",
 				i+1 < argc ? argv[i+1] : "{this_file}");
-	printf("}\n");
-	putmapping();			/* put out color mapping */
-	if (debugfp != NULL)		/* put out debug picture */
+		printf("#\t   Or: pcond [options] -m %s orig.hdr > output.hdr\n",
+				i+1 < argc ? argv[i+1] : "{this_file}");
+		for (j = 0; j < 24; j++)
+			printf("%f %f %f    %f %f %f\n",
+				colval(inpRGB[j],RED), colval(inpRGB[j],GRN),
+				colval(inpRGB[j],BLU), colval(mbRGB[j],RED),
+				colval(mbRGB[j],GRN), colval(mbRGB[j],BLU));
+		if (scanning && debugfp != NULL)
+			cwarp();		/* color warp for debugging */
+	} else {			/* print color mapping */
+						/* print header */
+		printf("{\n\tColor correction file computed by:\n\t\t");
+		printargs(argc, argv, stdout);
+		printf("\n\tUsage: pcomb -f %s uncorrected.hdr > corrected.hdr\n",
+				i+1 < argc ? argv[i+1] : "{this_file}");
+		if (!scanning)
+			printf("\t   Or: pcond [options] -f %s orig.hdr > output.hdr\n",
+					i+1 < argc ? argv[i+1] : "{this_file}");
+		printf("}\n");
+		putmapping();			/* put out color mapping */
+	}
+	if (debugfp != NULL) {		/* put out debug picture */
 		if (scanning)
 			picdebug();
 		else
 			clrdebug();
+	}
 	exit(0);
 userr:
 	fprintf(stderr,
-"Usage: %s [-d dbg.pic][-p xul yul xur yur xll yll xlr ylr] input.pic [output.cal]\n",
+"Usage: %s [-d dbg.hdr][-P | -p xul yul xur yur xll yll xlr ylr][-i irrad][-m] input.hdr [output.{cal|cwp}]\n",
 			progname);
-	fprintf(stderr, "   or: %s [-d dbg.pic] -c [xyY.dat [output.cal]]\n",
+	fprintf(stderr, "   or: %s [-d dbg.hdr][-i irrad][-m] -c [xyY.dat [output.{cal|cwp}]]\n",
 			progname);
 	exit(1);
+	return 1; /* pro forma return */
 }
 
 
-init()				/* initialize */
+static void
+init(void)				/* initialize */
 {
 	double	quad[4][2];
-	register int	i;
+	int	i;
 					/* make coordinate transformation */
 	quad[0][0] = bounds[0][0];
 	quad[0][1] = bounds[0][1];
@@ -236,15 +299,19 @@ init()				/* initialize */
 		exit(1);
 	}
 					/* map MacBeth colors to RGB space */
-	for (i = 0; i < 24; i++)
+	for (i = 0; i < 24; i++) {
 		xyY2RGB(mbRGB[i], mbxyY[i]);
+		scalecolor(mbRGB[i], irrad);
+	}
 }
 
 
-int
-chartndx(x, y, np)			/* find color number for position */
-int	x, y;
-int	*np;
+static int
+chartndx(			/* find color number for position */
+	int	x,
+	int y,
+	int	*np
+)
 {
 	double	ipos[3], cpos[3];
 	int	ix, iy;
@@ -256,16 +323,16 @@ int	*np;
 	mx3d_transform(ipos, imgxfm, cpos);
 	cpos[0] /= cpos[2];
 	cpos[1] /= cpos[2];
-	if (cpos[0] < 0. || cpos[0] >= 6. || cpos[1] < 0. || cpos[1] >= 4.)
+	if ((cpos[0] < 0.) | (cpos[0] >= 6.) | (cpos[1] < 0.) | (cpos[1] >= 4.))
 		return(RG_BORD);
 	ix = cpos[0];
 	iy = cpos[1];
 	fx = cpos[0] - ix;
 	fy = cpos[1] - iy;
 	*np = iy*6 + ix;
-	if (fx >= 0.35 && fx < 0.65 && fy >= 0.35 && fy < 0.65)
+	if ((fx >= 0.35) & (fx < 0.65) & (fy >= 0.35) & (fy < 0.65))
 		return(RG_CENT);
-	if (fx < 0.05 || fx >= 0.95 || fy < 0.05 || fy >= 0.95)
+	if ((fx < 0.05) | (fx >= 0.95) | (fy < 0.05) | (fy >= 0.95))
 		return(RG_BORD);
 	if (fx >= 0.5)			/* right side is corrected */
 		return(RG_CORR);
@@ -273,14 +340,15 @@ int	*np;
 }
 
 
-getpicture()				/* load in picture colors */
+static void
+getpicture(void)				/* load in picture colors */
 {
 	COLR	*scanln;
 	COLOR	pval;
 	int	ccount[24];
 	double	d;
 	int	y, i;
-	register int	x;
+	int	x;
 
 	scanln = (COLR *)malloc(xmax*sizeof(COLR));
 	if (scanln == NULL) {
@@ -311,11 +379,12 @@ getpicture()				/* load in picture colors */
 		scalecolor(inpRGB[i], d);
 		inpflags |= 1L<<i;
 	}
-	free((char *)scanln);
+	free((void *)scanln);
 }
 
 
-getcolors()			/* get xyY colors from standard input */
+static void
+getcolors(void)			/* get xyY colors from standard input */
 {
 	int	gotwhite = 0;
 	COLOR	whiteclr;
@@ -323,11 +392,11 @@ getcolors()			/* get xyY colors from standard input */
 	float	xyYin[3];
 
 	while (fgetval(stdin, 'i', &n) == 1) {		/* read colors */
-		if (n < 0 | n > 24 ||
+		if ((n < 0) | (n > 24) ||
 				fgetval(stdin, 'f', &xyYin[0]) != 1 ||
 				fgetval(stdin, 'f', &xyYin[1]) != 1 ||
 				fgetval(stdin, 'f', &xyYin[2]) != 1 ||
-				xyYin[0] < 0. | xyYin[1] < 0. ||
+				(xyYin[0] < 0.) | (xyYin[1] < 0.) ||
 				xyYin[0] + xyYin[1] > 1.) {
 			fprintf(stderr, "%s: bad color input data\n",
 					progname);
@@ -363,10 +432,13 @@ getcolors()			/* get xyY colors from standard input */
 }
 
 
-bresp(y, x)		/* piecewise linear interpolation of primaries */
-COLOR	y, x;
+static void
+bresp(		/* piecewise linear interpolation of primaries */
+	COLOR	y,
+	COLOR	x
+)
 {
-	register int	i, n;
+	int	i, n;
 
 	for (i = 0; i < 3; i++) {
 		for (n = 0; n < NMBNEU-2; n++)
@@ -381,12 +453,13 @@ COLOR	y, x;
 }
 
 
-compute()			/* compute color mapping */
+static void
+compute(void)			/* compute color mapping */
 {
 	COLOR	clrin[24], clrout[24];
 	long	cflags;
 	COLOR	ctmp;
-	register int	i, n;
+	int	i, n;
 					/* did we get what we need? */
 	if ((inpflags & REQFLGS) != REQFLGS) {
 		fprintf(stderr, "%s: missing required input colors\n",
@@ -396,18 +469,26 @@ compute()			/* compute color mapping */
 					/* compute piecewise luminance curve */
 	for (i = 0; i < NMBNEU; i++) {
 		copycolor(bramp[i][0], inpRGB[mbneu[i]]);
+		for (n = 3*(i>0); n--; )
+			if (colval(bramp[i][0],n) <=
+					colval(bramp[i-1][0],n)+1e-7) {
+				fprintf(stderr,
+		"%s: non-increasing neutral patch\n", progname);
+				exit(1);
+			}
 		copycolor(bramp[i][1], mbRGB[mbneu[i]]);
 	}
 					/* compute color space gamut */
 	if (scanning) {
 		copycolor(colmin, cblack);
 		copycolor(colmax, cwhite);
+		scalecolor(colmax, irrad);
 	} else
 		for (i = 0; i < 3; i++) {
 			colval(colmin,i) = colval(bramp[0][0],i) -
 				colval(bramp[0][1],i) *
 				(colval(bramp[1][0],i)-colval(bramp[0][0],i)) /
-				(colval(bramp[1][1],i)-colval(bramp[1][0],i));
+				(colval(bramp[1][1],i)-colval(bramp[0][1],i));
 			colval(colmax,i) = colval(bramp[NMBNEU-2][0],i) +
 				(1.-colval(bramp[NMBNEU-2][1],i)) *
 				(colval(bramp[NMBNEU-1][0],i) -
@@ -426,9 +507,8 @@ compute()			/* compute color mapping */
 				n++;
 			}
 		compsoln(clrin, clrout, n);
-						/* check out-of-gamut colors */
-		for (i = 0; i < 24; i++)
-			if (cflags & 1L<<i && cvtcolor(ctmp, mbRGB[i]))
+		for (i = 0; i < 24; i++)	/* check gamut */
+			if (cflags & 1L<<i && cvtcolor(ctmp, inpRGB[i]))
 				gmtflags |= 1L<<i;
 	} while (cflags & gmtflags);
 	if (gmtflags & MODFLGS)
@@ -438,10 +518,11 @@ compute()			/* compute color mapping */
 }
 
 
-putmapping()			/* put out color mapping for pcomb -f */
+static void
+putmapping(void)			/* put out color mapping */
 {
 	static char	cchar[3] = {'r', 'g', 'b'};
-	register int	i, j;
+	int	i, j;
 					/* print brightness mapping */
 	for (j = 0; j < 3; j++) {
 		printf("%cxa(i) : select(i", cchar[j]);
@@ -486,15 +567,18 @@ putmapping()			/* put out color mapping for pcomb -f *
 }
 
 
-compsoln(cin, cout, n)		/* solve 3xN system using least-squares */
-COLOR	cin[], cout[];
-int	n;
+static void
+compsoln(		/* solve 3xN system using least-squares */
+	COLOR	cin[],
+	COLOR	cout[],
+	int	n
+)
 {
 	extern double	mx3d_adjoint(), fabs();
 	double	mat[3][3], invmat[3][3];
 	double	det;
 	double	colv[3], rowv[3];
-	register int	i, j, k;
+	int	i, j, k;
 
 	if (n < 3) {
 		fprintf(stderr, "%s: too few colors to match!\n", progname);
@@ -546,14 +630,36 @@ int	n;
 }
 
 
-int
-cvtcolor(cout, cin)		/* convert color according to our mapping */
-COLOR	cout, cin;
+static void
+cwarp(void)				/* compute color warp map */
 {
+	int	i;
+
+	if ((wcor = new3dw(W3EXACT)) == NULL)
+		goto memerr;
+	for (i = 0; i < 24; i++)
+		if (!add3dpt(wcor, inpRGB[i], mbRGB[i]))
+			goto memerr;
+	return;
+memerr:
+	perror(progname);
+	exit(1);
+}
+
+
+static int
+cvtcolor(		/* convert color according to our mapping */
+	COLOR	cout,
+	COLOR	cin
+)
+{
 	COLOR	ctmp;
 	int	clipped;
 
-	if (scanning) {
+	if (wcor != NULL) {
+		clipped = warp3d(cout, cin, wcor);
+		clipped |= clipgamut(cout,bright(cout),CGAMUT,colmin,colmax);
+	} else if (scanning) {
 		bresp(ctmp, cin);
 		clipped = cresp(cout, ctmp);
 	} else {
@@ -564,18 +670,22 @@ COLOR	cout, cin;
 }
 
 
-int
-cresp(cout, cin)		/* transform color according to matrix */
-COLOR	cout, cin;
+static int
+cresp(		/* transform color according to matrix */
+	COLOR	cout,
+	COLOR	cin
+)
 {
 	colortrans(cout, solmat, cin);
 	return(clipgamut(cout, bright(cout), CGAMUT, colmin, colmax));
 }
 
 
-xyY2RGB(rgbout, xyYin)		/* convert xyY to RGB */
-COLOR	rgbout;
-register float	xyYin[3];
+static void
+xyY2RGB(		/* convert xyY to RGB */
+	COLOR	rgbout,
+	float	xyYin[3]
+)
 {
 	COLOR	ctmp;
 	double	d;
@@ -589,12 +699,13 @@ register float	xyYin[3];
 }
 
 
-picdebug()			/* put out debugging picture */
+static void
+picdebug(void)			/* put out debugging picture */
 {
 	static COLOR	blkcol = BLKCOLOR;
 	COLOR	*scan;
 	int	y, i;
-	register int	x, rg;
+	int	x, rg;
 
 	if (fseek(stdin, 0L, 0) == EOF) {
 		fprintf(stderr, "%s: cannot seek on input picture\n", progname);
@@ -625,7 +736,7 @@ picdebug()			/* put out debugging picture */
 				if (!(1L<<i & gmtflags) || (x+y)&07) {
 					copycolor(scan[x], mbRGB[i]);
 					clipgamut(scan[x], bright(scan[x]),
-						CGAMUT, cblack, cwhite);
+						CGAMUT, colmin, colmax);
 				} else
 					copycolor(scan[x], blkcol);
 			} else if (rg == RG_CORR)
@@ -641,18 +752,19 @@ picdebug()			/* put out debugging picture */
 	}
 						/* clean up */
 	fclose(debugfp);
-	free((char *)scan);
+	free((void *)scan);
 }
 
 
-clrdebug()			/* put out debug picture from color input */
+static void
+clrdebug(void)			/* put out debug picture from color input */
 {
 	static COLR	blkclr = BLKCOLR;
 	COLR	mbclr[24], cvclr[24], orclr[24];
 	COLR	*scan;
 	COLOR	ctmp, ct2;
 	int	y, i;
-	register int	x, rg;
+	int	x, rg;
 						/* convert colors */
 	for (i = 0; i < 24; i++) {
 		copycolor(ctmp, mbRGB[i]);
@@ -664,11 +776,17 @@ clrdebug()			/* put out debug picture from color input
 			clipgamut(ctmp, bright(ctmp), CGAMUT, cblack, cwhite);
 			setcolr(orclr[i], colval(ctmp,RED),
 					colval(ctmp,GRN), colval(ctmp,BLU));
-			bresp(ctmp, inpRGB[i]);
-			colortrans(ct2, solmat, ctmp);
-			clipgamut(ct2, bright(ct2), CGAMUT, cblack, cwhite);
-			setcolr(cvclr[i], colval(ct2,RED),
-					colval(ct2,GRN), colval(ct2,BLU));
+			if (rawmap)
+				copycolr(cvclr[i], mbclr[i]);
+			else {
+				bresp(ctmp, inpRGB[i]);
+				colortrans(ct2, solmat, ctmp);
+				clipgamut(ct2, bright(ct2), CGAMUT,
+						cblack, cwhite);
+				setcolr(cvclr[i], colval(ct2,RED),
+						colval(ct2,GRN),
+						colval(ct2,BLU));
+			}
 		}
 	}
 						/* allocate scanline */
@@ -705,5 +823,47 @@ clrdebug()			/* put out debug picture from color input
 	}
 						/* clean up */
 	fclose(debugfp);
-	free((char *)scan);
+	free((void *)scan);
+}
+
+
+static void
+getpos(		/* get boundary position */
+	char	*name,
+	int	bnds[2],
+	FILE	*fp
+)
+{
+	char	buf[64];
+
+	fprintf(stderr, "\tSelect corner: %s\n", name);
+	if (fgets(buf, sizeof(buf), fp) == NULL ||
+			sscanf(buf, "%d %d", &bnds[0], &bnds[1]) != 2) {
+		fprintf(stderr, "%s: read error from display process\n",
+				progname);
+		exit(1);
+	}
+}
+
+
+static void
+pickchartpos(		/* display picture and pick chart location */
+	char	*pfn
+)
+{
+	char	combuf[PATH_MAX];
+	FILE	*pfp;
+
+	sprintf(combuf, DISPCOM, pfn);
+	if ((pfp = popen(combuf, "r")) == NULL) {
+		perror(combuf);
+		exit(1);
+	}
+	fputs("Use middle mouse button to select chart corners:\n", stderr);
+	getpos("upper left (dark skin)", bounds[0], pfp);
+	getpos("upper right (bluish green)", bounds[1], pfp);
+	getpos("lower left (white)", bounds[2], pfp);
+	getpos("lower right (black)", bounds[3], pfp);
+	fputs("Got it -- quit display program.\n", stderr);
+	pclose(pfp);
 }