use the new halfsize func

tools/fimghalfsize.c

@@ -24,15 +24,15 @@ if (foo) {
 	}
 
 memset(&dst, 0, sizeof(FloatImg));
-foo = fimg_halfsize_0(&src, &dst, 0);
+foo = fimg_halfsize_1(&src, &dst, 0);
 if (foo) {
-	fprintf(stderr, "halfize fail -> %d\n", foo);
+	fprintf(stderr, "halfize 1 fail -> %d\n", foo);
 	return -1;
 	}
 
 if (to_gray) {
 	foo = fimg_to_gray(&dst);
-
+	/* and ? */
 	}
 
 foo = fimg_dump_to_file(&dst, oname, 0);
@@ -47,7 +47,10 @@ return -1;
 /* ------------------------------------------------------------- */
 void help(int u)
 {
-
+puts("Usage:\n\tfimghalfsize [options]  in.fimg out.fimg");
+puts("Options:");
+puts("\t-g\tconvert output to gray");
+exit(0);
 }
 /* ------------------------------------------------------------- */