diff --git a/rtengine/stdimagesource.cc b/rtengine/stdimagesource.cc
index 37d438863..298cf16ef 100644
--- a/rtengine/stdimagesource.cc
+++ b/rtengine/stdimagesource.cc
@@ -338,5 +338,10 @@ ColorTemp StdImageSource::getSpotWB (std::vector<Coord2D> &red, std::vector<Coor
     return ColorTemp (reds / rn * img_r, greens / gn * img_g, blues / bn * img_b, equal);
 }
 
+void StdImageSource::flushRGB() {
+    img->allocate(0, 0);
+};
+
+
 }
 
diff --git a/rtengine/stdimagesource.h b/rtengine/stdimagesource.h
index 500641f72..8f16880dc 100644
--- a/rtengine/stdimagesource.h
+++ b/rtengine/stdimagesource.h
@@ -101,6 +101,7 @@ public:
 
     void getRawValues(int x, int y, int rotate, int &R, int &G, int &B) override { R = G = B = 0;}
 
+    void        flushRGB          () override;
 
 };
 }