--- ray/src/px/aedimage.c	1990/01/26 08:17:29	1.7
+++ ray/src/px/aedimage.c	1991/04/18 14:35:03	1.10
@@ -99,6 +99,7 @@ long  scanpos[NROWS];
 
 extern double  atof();
 double  exposure = 1.0;
+int  wrong_fmt = 0;
 
 
 main(argc, argv)
@@ -140,7 +141,9 @@ char  *argv[];
 		quitmsg(errmsg);
 	}
 				/* get header */
-	getheader(fin, checkhead);
+	getheader(fin, checkhead, NULL);
+	if (wrong_fmt)
+		quitmsg("input must be a Radiance picture");
 				/* get picture dimensions */
 	if (fgetresolu(&xmax, &ymax, fin) != (YMAJOR|YDECR))
 		quitmsg("bad picture size");
@@ -169,8 +172,14 @@ userr:
 checkhead(line)				/* deal with line from header */
 char  *line;
 {
+	char	fmt[32];
+
 	if (isexpos(line))
 		exposure *= exposval(line);
+	else if (isformat(line)) {
+		formatval(fmt, line);
+		wrong_fmt = strcmp(fmt, COLRFMT);
+	}
 }
 
 
@@ -315,7 +324,7 @@ loopcom()				/* print pixel values interactively */
 				break;
 			case 'l':
 			case 'L':
-				printf("%-3gL", bright(cval)*683.0/exposure);
+				printf("%-3gL", luminance(cval)/exposure);
 				break;
 			case 'c':
 			case 'C':
@@ -515,7 +524,7 @@ colormap  map;
 	register int  i, val;
 
 	for (i = 0; i < 256; i++) {
-		val = pow(i/256.0, 1.0/GAMMA) * 256.0;
+		val = pow((i+0.5)/256.0, 1.0/GAMMA) * 256.0;
 		map[0][i] = map[1][i] = map[2][i] = val;
 	}
 }