fix a bug I introduced recently where YUV formats would crash the system
diff --git a/include/ui/PixelFormat.h b/include/ui/PixelFormat.h
index 607155c..f46f25c 100644
--- a/include/ui/PixelFormat.h
+++ b/include/ui/PixelFormat.h
@@ -90,7 +90,8 @@
         RGB                 = 2,
         RGBA                = 3,
         LUMINANCE           = 4,
-        LUMINANCE_ALPHA     = 5
+        LUMINANCE_ALPHA     = 5,
+        OTHER               = 0xFF
     };
 
     struct szinfo {