--- ray/src/common/colrops.c	1990/10/19 21:31:54	1.2
+++ ray/src/common/colrops.c	1992/02/18 15:25:55	2.2
@@ -10,7 +10,7 @@ static char SCCSid[] = "$SunId$ LBL";
 
 #include "color.h"
 
-#define MAXGSHIFT	4		/* maximum shift for gamma table */
+#define MAXGSHIFT	15		/* maximum shift for gamma table */
 
 static BYTE	g_mant[256], g_nexp[256];
 
@@ -128,8 +128,17 @@ register COLR	*scan;
 register int	len;
 register int	adjust;
 {
+	int	minexp;
+
+	if (adjust == 0)
+		return;
+	minexp = adjust < 0 ? -adjust : 0;
 	while (len-- > 0) {
-		scan[0][EXP] += adjust;
+		if (scan[0][EXP] <= minexp)
+			scan[0][RED] = scan[0][GRN] = scan[0][BLU] =
+			scan[0][EXP] = 0;
+		else
+			scan[0][EXP] += adjust;
 		scan++;
 	}
 }