--- ray/src/px/pcomb.c	1991/11/11 14:01:24	1.23
+++ ray/src/px/pcomb.c	1992/09/08 10:35:05	2.6
@@ -1,4 +1,4 @@
-/* Copyright (c) 1991 Regents of the University of California */
+/* Copyright (c) 1992 Regents of the University of California */
 
 #ifndef lint
 static char SCCSid[] = "$SunId$ LBL";
@@ -34,6 +34,7 @@ struct {
 
 int	nfiles;				/* number of input files */
 
+char	Command[] = "<Command>";
 char	vcolin[3][4] = {"ri", "gi", "bi"};
 char	vcolout[3][4] = {"ro", "go", "bo"};
 char	vbrtin[] = "li";
@@ -124,10 +125,13 @@ char	*argv[];
 				goto usage;
 			}
 		else {
-			input[nfiles].name = argv[a];
-			input[nfiles].fp = argv[a][0]=='!' ?
-					popen(argv[a]+1, "r") :
-					fopen(argv[a], "r");
+			if (argv[a][0] == '!') {
+				input[nfiles].name = Command;
+				input[nfiles].fp = popen(argv[a]+1, "r");
+			} else {
+				input[nfiles].name = argv[a];
+				input[nfiles].fp = fopen(argv[a], "r");
+			}
 			if (input[nfiles].fp == NULL) {
 				perror(argv[a]);
 				quit(1);
@@ -331,6 +335,7 @@ combine()			/* combine pictures */
 
 advance()			/* read in data for next scanline */
 {
+	extern double  fabs();
 	int	ytarget;
 	register COLOR	*st;
 	register int	i, j;
@@ -343,13 +348,16 @@ advance()			/* read in data for next scanline */
 			input[i].scan[0] = st;
 			if (yscan <= MIDSCN)		/* hit bottom? */
 				continue;
-			if (freadscan(st, xmax, input[i].fp) < 0) {	/* read */
+			if (freadscan(st, xmax, input[i].fp) < 0) {  /* read */
 				eputs(input[i].name);
 				eputs(": read error\n");
 				quit(1);
 			}
-			for (j = 0; j < xmax; j++)	/* adjust color */
-				multcolor(st[j], input[i].coef);
+			if (fabs(colval(input[i].coef,RED)-1.0) > 1e-3 ||
+				fabs(colval(input[i].coef,GRN)-1.0) > 1e-3 ||
+				fabs(colval(input[i].coef,BLU)-1.0) > 1e-3)
+				for (j = 0; j < xmax; j++)  /* adjust color */
+					multcolor(st[j], input[i].coef);
 		}
 }
 
@@ -446,8 +454,15 @@ char	*msg;
 }
 
 
-quit(code)
-int	code;
+quit(code)		/* exit gracefully */
+int  code;
 {
+	register int  i;
+				/* close input files */
+	for (i = 0; i < nfiles; i++)
+		if (input[i].name == Command)
+			pclose(input[i].fp);
+		else
+			fclose(input[i].fp);
 	exit(code);
 }