diff --git a/rtengine/filmnegativeproc.cc b/rtengine/filmnegativeproc.cc
index db98fdf02..7c7103dc6 100644
--- a/rtengine/filmnegativeproc.cc
+++ b/rtengine/filmnegativeproc.cc
@@ -150,16 +150,28 @@ void RawImageSource::filmNegativeProcess(const procparams::FilmNegativeParams &p
     // Chose an odd step, not multiple of the CFA size, to get a chance to visit each channel.
     if(ri->getSensorType() == ST_BAYER) {
         for (int row = 0; row < H; row+=5) {
-            for (int col = 0; col < W; col+=5) {
-                int c  = FC(row, col);                        // three colors,  0=R, 1=G,  2=B
-                cvs[c].push_back(rawData[row][col]);
+            int col = 0;
+            int c0 = FC(row, col);
+            int c1 = FC(row, col + 5);
+            for (; col < W - 5; col+=10) {
+                cvs[c0].push_back(rawData[row][col]);
+                cvs[c1].push_back(rawData[row][col + 5]);
+            }
+            if (col < W) {
+                cvs[c0].push_back(rawData[row][col]);
             }
         }
     } else if(ri->getSensorType() == ST_FUJI_XTRANS) {
         for (int row = 0; row < H; row+=5) {
-            for (int col = 0; col < W; col+=5) {
-                int c  = ri->XTRANSFC(row, col);                        // three colors,  0=R, 1=G,  2=B
-                cvs[c].push_back(rawData[row][col]);
+            int col = 0;
+            const unsigned int cs[6] = {ri->XTRANSFC(row, 0), ri->XTRANSFC(row, 5), ri->XTRANSFC(row, 10), ri->XTRANSFC(row, 15), ri->XTRANSFC(row, 20), ri->XTRANSFC(row, 25)};
+            for (; col < W - 25; col += 30) {
+                for (int c = 0; c < 6; ++c) {
+                    cvs[cs[c]].push_back(rawData[row][col + c * 5]);
+                }
+            }
+            for (int c = 0; col < W; col += 5, ++c) {
+                cvs[cs[c]].push_back(rawData[row][col]);
             }
         }
     }