diff --git a/rtengine/rawimagesource.cc b/rtengine/rawimagesource.cc
index da89810c4..1f84cad54 100644
--- a/rtengine/rawimagesource.cc
+++ b/rtengine/rawimagesource.cc
@@ -4720,10 +4720,14 @@ void RawImageSource::getRAWHistogram (LUTu & histRedRaw, LUTu & histGreenRaw, LU
     histRedRaw.clear();
     histGreenRaw.clear();
     histBlueRaw.clear();
-    const float mult[4] = { 255.0f / Color::gamma(ri->get_white(0) - cblacksom[0]),
-                            255.0f / Color::gamma(ri->get_white(1) - cblacksom[1]),
-                            255.0f / Color::gamma(ri->get_white(2) - cblacksom[2]),
-                            255.0f / Color::gamma(ri->get_white(3) - cblacksom[3])
+
+    const float maxWhite = rtengine::max(ri->get_white(0), ri->get_white(1), ri->get_white(2), ri->get_white(3));
+    const float scale = maxWhite <= 1.f ? 65535.f : 1.f; // special case for float raw images in [0.0;1.0] range
+    const float multScale = maxWhite <= 1.f ? 1.f / 255.f : 255.f;
+    const float mult[4] = { multScale / (ri->get_white(0) - cblacksom[0]),
+                            multScale / (ri->get_white(1) - cblacksom[1]),
+                            multScale / (ri->get_white(2) - cblacksom[2]),
+                            multScale / (ri->get_white(3) - cblacksom[3])
                           };
 
     const bool fourColours = ri->getSensorType() == ST_BAYER && ((mult[1] != mult[3] || cblacksom[1] != cblacksom[3]) || FC(0, 0) == 3 || FC(0, 1) == 3 || FC(1, 0) == 3 || FC(1, 1) == 3);
@@ -4787,26 +4791,26 @@ void RawImageSource::getRAWHistogram (LUTu & histRedRaw, LUTu & histGreenRaw, LU
                 c2 = ( fourColours && c2 == 1 && !(i & 1) ) ? 3 : c2;
 
                 for (j = start; j < end - 1; j += 2) {
-                    tmphist[c1][(int)ri->data[i][j]]++;
-                    tmphist[c2][(int)ri->data[i][j + 1]]++;
+                    tmphist[c1][(int)(ri->data[i][j] * scale)]++;
+                    tmphist[c2][(int)(ri->data[i][j + 1] * scale)]++;
                 }
 
                 if(j < end) { // last pixel of row if width is odd
-                    tmphist[c1][(int)ri->data[i][j]]++;
+                    tmphist[c1][(int)(ri->data[i][j] * scale)]++;
                 }
             } else if (ri->get_colors() == 1) {
                 for (int j = start; j < end; j++) {
-                    tmphist[0][(int)ri->data[i][j]]++;
+                    tmphist[0][(int)(ri->data[i][j] * scale)]++;
                 }
             } else if(ri->getSensorType() == ST_FUJI_XTRANS) {
                 for (int j = start; j < end - 1; j += 2) {
                     int c = ri->XTRANSFC(i, j);
-                    tmphist[c][(int)ri->data[i][j]]++;
+                    tmphist[c][(int)(ri->data[i][j] * scale)]++;
                 }
             } else {
                 for (int j = start; j < end; j++) {
                     for (int c = 0; c < 3; c++) {
-                        tmphist[c][(int)ri->data[i][3 * j + c]]++;
+                        tmphist[c][(int)(ri->data[i][3 * j + c] * scale)]++;
                     }
                 }
             }
@@ -4829,21 +4833,20 @@ void RawImageSource::getRAWHistogram (LUTu & histRedRaw, LUTu & histGreenRaw, LU
         } // end of critical region
     } // end of parallel region
 
-    for(int i = 0; i < 65536; i++) {
-        int idx;
-        idx = (int)std::min(255.0f, mult[0] * Color::gamma(std::max(0.0f, i - cblacksom[0])));
+    for(int i = 0; i < histoSize; i++) {
+        int idx = std::min(255.f, mult[0] * std::max(0.f, i - cblacksom[0]));
         histRedRaw[idx] += hist[0][i];
 
         if (ri->get_colors() > 1) {
-            idx = (int)std::min(255.0f, mult[1] * Color::gamma(std::max(0.0f, i - cblacksom[1])));
+            idx = std::min(255.f, mult[1] * std::max(0.f, i - cblacksom[1]));
             histGreenRaw[idx] += hist[1][i];
 
             if (fourColours) {
-                idx = (int)std::min(255.0f, mult[3] * Color::gamma(std::max(0.0f, i - cblacksom[3])));
+                idx = std::min(255.f, mult[3] * std::max(0.f, i - cblacksom[3]));
                 histGreenRaw[idx] += hist[3][i];
             }
 
-            idx = (int)std::min(255.0f, mult[2] * Color::gamma(std::max(0.0f, i - cblacksom[2])));
+            idx = std::min(255.f, mult[2] * std::max(0.f, i - cblacksom[2]));
             histBlueRaw[idx] += hist[2][i];
         }
     }