--- ray/src/px/ra_t8.c	1990/03/12 15:14:46	1.7
+++ ray/src/px/ra_t8.c	1991/04/18 14:35:45	1.9
@@ -125,6 +125,7 @@ char  *argv[];
 		}
 					/* put header */
 		printargs(i, argv, stdout);
+		fputformat(COLRFMT, stdout);
 		putchar('\n');
 		fputresolu(YMAJOR|YDECR, xmax, ymax, stdout);
 					/* convert file */
@@ -282,10 +283,10 @@ register struct hdStruct  *h;
 		p->fp = stdin;
 	else if ((p->fp = fopen(fname, "r")) == NULL)
 		return(NULL);
-					/* discard header */
-	getheader(p->fp, NULL);
-	if (fgetresolu(&xmax, &ymax, p->fp) != (YMAJOR|YDECR))
-		quiterr("bad picture size");
+					/* get header info. */
+	if (checkheader(p->fp, COLRFMT, NULL) < 0 ||
+			fgetresolu(&xmax, &ymax, p->fp) != (YMAJOR|YDECR))
+		quiterr("bad picture format");
 	p->nexty = 0;
 	p->bytes_line = 0;		/* variable length lines */
 	p->pos.y = (long *)ecalloc(ymax, sizeof(long));
@@ -465,7 +466,7 @@ 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;
 	}
 }