diff --git a/backend/genesys/command_set.h b/backend/genesys/command_set.h
index 0b1591a9c..4e22a562c 100644
--- a/backend/genesys/command_set.h
+++ b/backend/genesys/command_set.h
@@ -67,8 +67,7 @@ public:
     virtual void init(Genesys_Device* dev) const = 0;
 
     virtual void init_regs_for_warmup(Genesys_Device* dev, const Genesys_Sensor& sensor,
-                                      Genesys_Register_Set* regs, int* channels,
-                                      int* total_size) const = 0;
+                                      Genesys_Register_Set* regs) const = 0;
 
     virtual void init_regs_for_shading(Genesys_Device* dev, const Genesys_Sensor& sensor,
                                        Genesys_Register_Set& regs) const = 0;
diff --git a/backend/genesys/genesys.cpp b/backend/genesys/genesys.cpp
index ab2f8d62c..a8440f167 100644
--- a/backend/genesys/genesys.cpp
+++ b/backend/genesys/genesys.cpp
@@ -3428,18 +3428,20 @@ static void genesys_warmup_lamp(Genesys_Device* dev)
 {
     DBG_HELPER(dbg);
     unsigned seconds = 0;
-  int pixel;
-  int channels, total_size;
   double first_average = 0;
   double second_average = 0;
   int difference = 255;
-    int lines = 3;
 
   const auto& sensor = sanei_genesys_find_sensor_any(dev);
 
-    dev->cmd_set->init_regs_for_warmup(dev, sensor, &dev->reg, &channels, &total_size);
+    dev->cmd_set->init_regs_for_warmup(dev, sensor, &dev->reg);
     dev->interface->write_registers(dev->reg);
 
+    auto total_pixels =  dev->session.output_pixels;
+    auto total_size = dev->session.output_line_bytes;
+    auto channels = dev->session.params.channels;
+    auto lines = dev->session.output_line_count;
+
   std::vector<uint8_t> first_line(total_size);
   std::vector<uint8_t> second_line(total_size);
 
@@ -3476,8 +3478,7 @@ static void genesys_warmup_lamp(Genesys_Device* dev)
         dev->cmd_set->end_scan(dev, &dev->reg, true);
 
       /* compute difference between the two scans */
-      for (pixel = 0; pixel < total_size; pixel++)
-	{
+        for (unsigned pixel = 0; pixel < total_size; pixel++) {
             // 16 bit data
             if (dev->session.params.depth == 16) {
 	      first_average += (first_line[pixel] + first_line[pixel + 1] * 256);
@@ -3488,11 +3489,13 @@ static void genesys_warmup_lamp(Genesys_Device* dev)
 	    {
 	      first_average += first_line[pixel];
 	      second_average += second_line[pixel];
-	    }
-	}
+            }
+        }
+
+        first_average /= total_pixels;
+        second_average /= total_pixels;
+
         if (dev->session.params.depth == 16) {
-	  first_average /= pixel;
-	  second_average /= pixel;
             difference = static_cast<int>(std::fabs(first_average - second_average));
 	  DBG(DBG_info, "%s: average = %.2f, diff = %.3f\n", __func__,
 	      100 * ((second_average) / (256 * 256)),
@@ -3501,11 +3504,8 @@ static void genesys_warmup_lamp(Genesys_Device* dev)
 	  if (second_average > (100 * 256)
 	      && (difference / second_average) < 0.002)
 	    break;
-	}
-      else
-	{
-	  first_average /= pixel;
-	  second_average /= pixel;
+        } else {
+
 	  if (DBG_LEVEL >= DBG_data)
 	    {
               sanei_genesys_write_pnm_file("gl_warmup1.pnm", first_line.data(), 8, channels,
@@ -3519,7 +3519,7 @@ static void genesys_warmup_lamp(Genesys_Device* dev)
 	  if (fabs (first_average - second_average) < 15
 	      && second_average > 55)
 	    break;
-	}
+        }
 
       /* sleep another second before next loop */
         dev->interface->sleep_ms(1000);
diff --git a/backend/genesys/gl124.cpp b/backend/genesys/gl124.cpp
index b6beefb45..7f6010686 100644
--- a/backend/genesys/gl124.cpp
+++ b/backend/genesys/gl124.cpp
@@ -1418,13 +1418,9 @@ void CommandSetGl124::coarse_gain_calibration(Genesys_Device* dev, const Genesys
 // wait for lamp warmup by scanning the same line until difference
 // between 2 scans is below a threshold
 void CommandSetGl124::init_regs_for_warmup(Genesys_Device* dev, const Genesys_Sensor& sensor,
-                                           Genesys_Register_Set* reg, int* channels,
-                                           int* total_size) const
+                                           Genesys_Register_Set* reg) const
 {
     DBG_HELPER(dbg);
-  int num_pixels;
-
-  *channels=3;
 
   *reg = dev->reg;
 
@@ -1436,7 +1432,7 @@ void CommandSetGl124::init_regs_for_warmup(Genesys_Device* dev, const Genesys_Se
     session.params.pixels = dev->model->x_size_calib_mm * sensor.optical_res / MM_PER_INCH / 2;
     session.params.lines = 1;
     session.params.depth = 8;
-    session.params.channels = *channels;
+    session.params.channels = 3;
     session.params.scan_method = dev->settings.scan_method;
     session.params.scan_mode = ScanColorMode::COLOR_SINGLE_PASS;
     session.params.color_filter = dev->settings.color_filter;
@@ -1449,10 +1445,6 @@ void CommandSetGl124::init_regs_for_warmup(Genesys_Device* dev, const Genesys_Se
 
     init_regs_for_scan_session(dev, sensor, reg, session);
 
-    num_pixels = session.output_pixels;
-
-  *total_size = num_pixels * 3 * 1;        /* colors * bytes_per_color * scan lines */
-
   sanei_genesys_set_motor_power(*reg, false);
 }
 
diff --git a/backend/genesys/gl124.h b/backend/genesys/gl124.h
index 9f6da50c3..df50c12d6 100644
--- a/backend/genesys/gl124.h
+++ b/backend/genesys/gl124.h
@@ -93,8 +93,7 @@ public:
     void init(Genesys_Device* dev) const override;
 
     void init_regs_for_warmup(Genesys_Device* dev, const Genesys_Sensor& sensor,
-                              Genesys_Register_Set* regs, int* channels,
-                              int* total_size) const override;
+                              Genesys_Register_Set* regs) const override;
 
     void init_regs_for_shading(Genesys_Device* dev, const Genesys_Sensor& sensor,
                                Genesys_Register_Set& regs) const override;
diff --git a/backend/genesys/gl646.cpp b/backend/genesys/gl646.cpp
index da8c4b448..65ee5ae0d 100644
--- a/backend/genesys/gl646.cpp
+++ b/backend/genesys/gl646.cpp
@@ -2458,14 +2458,12 @@ void CommandSetGl646::coarse_gain_calibration(Genesys_Device* dev, const Genesys
  *
  */
 void CommandSetGl646::init_regs_for_warmup(Genesys_Device* dev, const Genesys_Sensor& sensor,
-                                           Genesys_Register_Set* local_reg, int* channels,
-                                           int* total_size) const
+                                           Genesys_Register_Set* local_reg) const
 {
     DBG_HELPER(dbg);
     (void) sensor;
 
   Genesys_Settings settings;
-  int lines;
 
   dev->frontend = dev->frontend_initial;
 
@@ -2504,11 +2502,6 @@ void CommandSetGl646::init_regs_for_warmup(Genesys_Device* dev, const Genesys_Se
   /* turn off motor during this scan */
   sanei_genesys_set_motor_power(*local_reg, false);
 
-  /* returned value to higher level warmup function */
-  *channels = 1;
-    lines = local_reg->get24(REG_LINCNT) + 1;
-  *total_size = lines * settings.pixels;
-
     // now registers are ok, write them to scanner
     gl646_set_fe(dev, local_sensor, AFE_SET, settings.xres);
 }
diff --git a/backend/genesys/gl646.h b/backend/genesys/gl646.h
index ad9a1104f..dea4bffca 100644
--- a/backend/genesys/gl646.h
+++ b/backend/genesys/gl646.h
@@ -446,8 +446,7 @@ public:
     void init(Genesys_Device* dev) const override;
 
     void init_regs_for_warmup(Genesys_Device* dev, const Genesys_Sensor& sensor,
-                              Genesys_Register_Set* regs, int* channels,
-                              int* total_size) const override;
+                              Genesys_Register_Set* regs) const override;
 
     void init_regs_for_shading(Genesys_Device* dev, const Genesys_Sensor& sensor,
                                Genesys_Register_Set& regs) const override;
diff --git a/backend/genesys/gl841.cpp b/backend/genesys/gl841.cpp
index 9a364bf67..61d6ca08f 100644
--- a/backend/genesys/gl841.cpp
+++ b/backend/genesys/gl841.cpp
@@ -2834,8 +2834,7 @@ void CommandSetGl841::coarse_gain_calibration(Genesys_Device* dev, const Genesys
 // wait for lamp warmup by scanning the same line until difference
 // between 2 scans is below a threshold
 void CommandSetGl841::init_regs_for_warmup(Genesys_Device* dev, const Genesys_Sensor& sensor,
-                                           Genesys_Register_Set* local_reg, int* channels,
-                                           int* total_size) const
+                                           Genesys_Register_Set* local_reg) const
 {
     DBG_HELPER(dbg);
     int num_pixels = 4 * 300;
@@ -2857,13 +2856,9 @@ void CommandSetGl841::init_regs_for_warmup(Genesys_Device* dev, const Genesys_Se
     session.params.pixels = num_pixels;
     session.params.lines = 1;
     session.params.depth = 16;
-    session.params.channels = *channels;
+    session.params.channels = 3;
     session.params.scan_method = dev->settings.scan_method;
-    if (*channels == 3) {
-        session.params.scan_mode = ScanColorMode::COLOR_SINGLE_PASS;
-    } else {
-        session.params.scan_mode = ScanColorMode::GRAY;
-    }
+    session.params.scan_mode = ScanColorMode::COLOR_SINGLE_PASS;
     session.params.color_filter = dev->settings.color_filter;
     session.params.flags = ScanFlag::DISABLE_SHADING |
                            ScanFlag::DISABLE_GAMMA |
@@ -2873,10 +2868,6 @@ void CommandSetGl841::init_regs_for_warmup(Genesys_Device* dev, const Genesys_Se
     compute_session(dev, session, sensor);
 
     init_regs_for_scan_session(dev, sensor, local_reg, session);
-
-    num_pixels = session.output_pixels;
-
-  *total_size = num_pixels * 3 * 2 * 1;	/* colors * bytes_per_color * scan lines */
 }
 
 /*
diff --git a/backend/genesys/gl841.h b/backend/genesys/gl841.h
index 9e010bb30..a66bb80a0 100644
--- a/backend/genesys/gl841.h
+++ b/backend/genesys/gl841.h
@@ -60,8 +60,7 @@ public:
     void init(Genesys_Device* dev) const override;
 
     void init_regs_for_warmup(Genesys_Device* dev, const Genesys_Sensor& sensor,
-                              Genesys_Register_Set* regs, int* channels,
-                              int* total_size) const override;
+                              Genesys_Register_Set* regs) const override;
 
     void init_regs_for_shading(Genesys_Device* dev, const Genesys_Sensor& sensor,
                                Genesys_Register_Set& regs) const override;
diff --git a/backend/genesys/gl843.cpp b/backend/genesys/gl843.cpp
index 68a72ab5d..b3fd73e57 100644
--- a/backend/genesys/gl843.cpp
+++ b/backend/genesys/gl843.cpp
@@ -1757,20 +1757,18 @@ void CommandSetGl843::coarse_gain_calibration(Genesys_Device* dev, const Genesys
 // wait for lamp warmup by scanning the same line until difference
 // between 2 scans is below a threshold
 void CommandSetGl843::init_regs_for_warmup(Genesys_Device* dev, const Genesys_Sensor& sensor,
-                                           Genesys_Register_Set* reg, int* channels,
-                                           int* total_size) const
+                                           Genesys_Register_Set* reg) const
 {
     DBG_HELPER(dbg);
     (void) sensor;
 
-    *channels=3;
+    unsigned channels = 3;
     unsigned resolution = dev->model->get_resolution_settings(dev->settings.scan_method)
                                      .get_nearest_resolution_x(600);
 
-  const auto& calib_sensor = sanei_genesys_find_sensor(dev, resolution, *channels,
+  const auto& calib_sensor = sanei_genesys_find_sensor(dev, resolution, channels,
                                                        dev->settings.scan_method);
     unsigned num_pixels = dev->model->x_size_calib_mm * resolution / MM_PER_INCH / 2;
-  *total_size = num_pixels * 3 * 1;
 
   *reg = dev->reg;
 
@@ -1782,7 +1780,7 @@ void CommandSetGl843::init_regs_for_warmup(Genesys_Device* dev, const Genesys_Se
     session.params.pixels = num_pixels;
     session.params.lines = 1;
     session.params.depth = 8;
-    session.params.channels = *channels;
+    session.params.channels = channels;
     session.params.scan_method = dev->settings.scan_method;
     session.params.scan_mode = ScanColorMode::COLOR_SINGLE_PASS;
     session.params.color_filter = dev->settings.color_filter;
diff --git a/backend/genesys/gl843.h b/backend/genesys/gl843.h
index 7cd46fcab..d227af2d9 100644
--- a/backend/genesys/gl843.h
+++ b/backend/genesys/gl843.h
@@ -60,8 +60,7 @@ public:
     void init(Genesys_Device* dev) const override;
 
     void init_regs_for_warmup(Genesys_Device* dev, const Genesys_Sensor& sensor,
-                              Genesys_Register_Set* regs, int* channels,
-                              int* total_size) const override;
+                              Genesys_Register_Set* regs) const override;
 
     void init_regs_for_shading(Genesys_Device* dev, const Genesys_Sensor& sensor,
                                Genesys_Register_Set& regs) const override;
diff --git a/backend/genesys/gl846.cpp b/backend/genesys/gl846.cpp
index c22b3cd9c..aff036955 100644
--- a/backend/genesys/gl846.cpp
+++ b/backend/genesys/gl846.cpp
@@ -1392,14 +1392,11 @@ bool CommandSetGl846::needs_home_before_init_regs_for_scan(Genesys_Device* dev)
 }
 
 void CommandSetGl846::init_regs_for_warmup(Genesys_Device* dev, const Genesys_Sensor& sensor,
-                                           Genesys_Register_Set* regs, int* channels,
-                                           int* total_size) const
+                                           Genesys_Register_Set* regs) const
 {
     (void) dev;
     (void) sensor;
     (void) regs;
-    (void) channels;
-    (void) total_size;
     throw SaneException("not implemented");
 }
 
diff --git a/backend/genesys/gl846.h b/backend/genesys/gl846.h
index bfc214c0a..742a7c5f1 100644
--- a/backend/genesys/gl846.h
+++ b/backend/genesys/gl846.h
@@ -60,8 +60,7 @@ public:
     void init(Genesys_Device* dev) const override;
 
     void init_regs_for_warmup(Genesys_Device* dev, const Genesys_Sensor& sensor,
-                              Genesys_Register_Set* regs, int* channels,
-                              int* total_size) const override;
+                              Genesys_Register_Set* regs) const override;
 
     void init_regs_for_shading(Genesys_Device* dev, const Genesys_Sensor& sensor,
                                Genesys_Register_Set& regs) const override;
diff --git a/backend/genesys/gl847.cpp b/backend/genesys/gl847.cpp
index b41e4e127..305f6836a 100644
--- a/backend/genesys/gl847.cpp
+++ b/backend/genesys/gl847.cpp
@@ -1288,14 +1288,11 @@ bool CommandSetGl847::needs_home_before_init_regs_for_scan(Genesys_Device* dev)
 }
 
 void CommandSetGl847::init_regs_for_warmup(Genesys_Device* dev, const Genesys_Sensor& sensor,
-                                           Genesys_Register_Set* regs, int* channels,
-                                           int* total_size) const
+                                           Genesys_Register_Set* regs) const
 {
     (void) dev;
     (void) sensor;
     (void) regs;
-    (void) channels;
-    (void) total_size;
     throw SaneException("not implemented");
 }
 
diff --git a/backend/genesys/gl847.h b/backend/genesys/gl847.h
index 794aa3ebf..7a5f954b1 100644
--- a/backend/genesys/gl847.h
+++ b/backend/genesys/gl847.h
@@ -80,8 +80,7 @@ public:
     void init(Genesys_Device* dev) const override;
 
     void init_regs_for_warmup(Genesys_Device* dev, const Genesys_Sensor& sensor,
-                              Genesys_Register_Set* regs, int* channels,
-                              int* total_size) const override;
+                              Genesys_Register_Set* regs) const override;
 
     void init_regs_for_shading(Genesys_Device* dev, const Genesys_Sensor& sensor,
                                Genesys_Register_Set& regs) const override;