diff --git a/src/common/QskRgbValue.cpp b/src/common/QskRgbValue.cpp
index 5dcb8b45..0b76f42f 100644
--- a/src/common/QskRgbValue.cpp
+++ b/src/common/QskRgbValue.cpp
@@ -153,3 +153,22 @@ QRgb QskRgbValue::rgb( Qt::GlobalColor color )
 
     return rgbValues[ color ];
 }
+
+QRgb QskRgbValue::lighter( QRgb rgb, int factor ) noexcept
+{
+    if ( factor <= 0 )
+        return rgb;
+
+    // guess we can find a faster implementation without using QColor TODO ...
+    return QColor::fromRgba( rgb ).lighter( factor ).rgba();
+}
+
+QRgb QskRgbValue::darker( QRgb rgb, int factor ) noexcept
+{   
+    if ( factor <= 0 )                                
+        return rgb;
+
+    // guess we can find a faster implementation without using QColor TODO ...
+    return QColor::fromRgba( rgb ).darker( factor ).rgba();
+}
+
diff --git a/src/common/QskRgbValue.h b/src/common/QskRgbValue.h
index 28926b50..48e4e7b5 100644
--- a/src/common/QskRgbValue.h
+++ b/src/common/QskRgbValue.h
@@ -437,7 +437,7 @@
 
 namespace QskRgbValue
 {
-#define RGB( name, value ) static constexpr const unsigned int name = value;
+#define RGB( name, value ) static constexpr const QRgb name = value;
     QSK_RGB_VALUES
 #undef RGB
 
@@ -460,6 +460,9 @@ namespace QskRgbValue
     {
         return ( rgb & ColorMask ) | ( ( static_cast< uint >( alpha ) & 0xffu ) << 24 );
     }
+
+    QSK_EXPORT QRgb lighter( QRgb, int factor = 150 ) noexcept;
+    QSK_EXPORT QRgb darker( QRgb, int factor = 200 ) noexcept;
 }
 
 #endif