diff --git a/rtdata/languages/default b/rtdata/languages/default
index fb024b3d5..5ec37ce8b 100644
--- a/rtdata/languages/default
+++ b/rtdata/languages/default
@@ -1874,7 +1874,8 @@ TP_RAW_HD_TOOLTIP;Lower values make hot/dead pixel detection more aggressive, bu
 TP_RAW_HPHD;HPHD
 TP_RAW_IGV;IGV
 TP_RAW_IMAGENUM;Sub-image
-TP_RAW_IMAGENUM_TOOLTIP;Some raw files consist of several sub-images (Pentax/Sony Pixel Shift, Pentax 3-in-1 HDR, Canon Dual Pixel).\n\nWhen using any demosaicing method other than Pixel Shift, this selects which sub-image is used.\n\nWhen using the Pixel Shift demosaicing method on a Pixel Shift raw, all sub-images are used, and this selects which sub-image should be used for moving parts.
+TP_RAW_IMAGENUM_SN;SN mode
+TP_RAW_IMAGENUM_TOOLTIP;Some raw files consist of several sub-images (Pentax/Sony Pixel Shift, Pentax 3-in-1 HDR, Canon Dual Pixel, Fuji EXR).\n\nWhen using any demosaicing method other than Pixel Shift, this selects which sub-image is used.\n\nWhen using the Pixel Shift demosaicing method on a Pixel Shift raw, all sub-images are used, and this selects which sub-image should be used for moving parts.
 TP_RAW_LABEL;Demosaicing
 TP_RAW_LMMSE;LMMSE
 TP_RAW_LMMSEITERATIONS;LMMSE enhancement steps
diff --git a/rtengine/rawimagesource.cc b/rtengine/rawimagesource.cc
index f551eb0dc..79922adbd 100644
--- a/rtengine/rawimagesource.cc
+++ b/rtengine/rawimagesource.cc
@@ -1793,6 +1793,19 @@ void RawImageSource::preprocess  (const RAWParams &raw, const LensProfParams &le
                 copyOriginalPixels(raw, riFrames[i], rid, rif, *rawDataFrames[i]);
             }
         }
+    } else if (numFrames == 2 && currFrame == 2) { // average the frames
+        if(!rawDataBuffer[0]) {
+            rawDataBuffer[0] = new array2D<float>;
+        }
+        rawDataFrames[1] = rawDataBuffer[0];
+        copyOriginalPixels(raw, riFrames[1], rid, rif, *rawDataFrames[1]);
+        copyOriginalPixels(raw, ri, rid, rif, rawData);
+
+        for (int i = 0; i < H; ++i) {
+            for (int j = 0; j < W; ++j) {
+                rawData[i][j] = (rawData[i][j] + (*rawDataFrames[1])[i][j]) * 0.5f;
+            }
+        }
     } else {
         copyOriginalPixels(raw, ri, rid, rif, rawData);
     }
diff --git a/rtengine/rawimagesource.h b/rtengine/rawimagesource.h
index a23e9c3cb..2c83b9bd3 100644
--- a/rtengine/rawimagesource.h
+++ b/rtengine/rawimagesource.h
@@ -201,8 +201,13 @@ public:
     static void init ();
     static void cleanup ();
     void setCurrentFrame(unsigned int frameNum) override {
-        currFrame = std::min(numFrames - 1, frameNum);
-        ri = riFrames[currFrame];
+        if (numFrames == 2 && frameNum == 2) { // special case for averaging of two frames
+            currFrame = frameNum;
+            ri = riFrames[0];
+        } else  {
+            currFrame = std::min(numFrames - 1, frameNum);
+            ri = riFrames[currFrame];
+        }
     }
     int getFrameCount() override {return numFrames;}
     int getFlatFieldAutoClipValue() override {return flatFieldAutoClipValue;}
diff --git a/rtgui/bayerprocess.cc b/rtgui/bayerprocess.cc
index 74cf27dde..279e68bd6 100644
--- a/rtgui/bayerprocess.cc
+++ b/rtgui/bayerprocess.cc
@@ -730,7 +730,10 @@ void BayerProcess::FrameCountChanged(int n, int frameNum)
                 entry << i;
                 imageNumber->append(entry.str());
             }
-            imageNumber->set_active(std::min(frameNum, n - 1));
+            if (n == 2) {
+                imageNumber->append(M("TP_RAW_IMAGENUM_SN"));
+            }
+            imageNumber->set_active(std::min(frameNum, n == 2 ? n : n - 1));
             if (n == 1) {
                 imageNumberBox->hide();
             } else {