diff --git a/backend/genesys/genesys.cpp b/backend/genesys/genesys.cpp
index fbb30fbbb..79d6b3afd 100644
--- a/backend/genesys/genesys.cpp
+++ b/backend/genesys/genesys.cpp
@@ -1087,7 +1087,7 @@ void scanner_move_back_home(Genesys_Device& dev, bool wait_until_home)
     ScanSession session;
     session.params.xres = resolution;
     session.params.yres = resolution;
-    session.params.startx = 100;
+    session.params.startx = 100 * resolution / sensor.optical_res;
     if (dev.model->asic_type == AsicType::GL843) {
         session.params.starty = 40000;
     } else {
@@ -1234,7 +1234,7 @@ void scanner_move_back_home_ta(Genesys_Device& dev)
     ScanSession session;
     session.params.xres = resolution;
     session.params.yres = resolution;
-    session.params.startx = 100;
+    session.params.startx = 100 * resolution / sensor.optical_res;
     session.params.starty = 30000;
     session.params.pixels = 100;
     session.params.lines = 100;
@@ -1674,7 +1674,10 @@ static void genesys_shading_calibration_impl(Genesys_Device* dev, const Genesys_
     }
     unsigned channels = dev->calib_session.params.channels;
 
-    unsigned out_pixels_per_line = pixels_per_line + dev->calib_session.params.startx;
+    // BUG: we are using wrong pixel number here
+    unsigned start_offset =
+            dev->calib_session.params.startx * sensor.optical_res / dev->calib_session.params.xres;
+    unsigned out_pixels_per_line = pixels_per_line + start_offset;
 
     // FIXME: we set this during both dark and white calibration. A cleaner approach should
     // probably be used
@@ -1749,10 +1752,10 @@ static void genesys_shading_calibration_impl(Genesys_Device* dev, const Genesys_
     }
 
     std::fill(out_average_data.begin(),
-              out_average_data.begin() + dev->calib_session.params.startx * channels, 0);
+              out_average_data.begin() + start_offset * channels, 0);
 
     compute_array_percentile_approx(out_average_data.data() +
-                                        dev->calib_session.params.startx * channels,
+                                        start_offset * channels,
                                     calibration_data.data(),
                                     dev->calib_session.params.lines, pixels_per_line * channels,
                                     0.5f);
@@ -1799,7 +1802,11 @@ static void genesys_dummy_dark_shading(Genesys_Device* dev, const Genesys_Sensor
 
     unsigned channels = dev->calib_session.params.channels;
 
-    unsigned out_pixels_per_line = pixels_per_line + dev->calib_session.params.startx;
+    // BUG: we are using wrong pixel number here
+    unsigned start_offset =
+            dev->calib_session.params.startx * sensor.optical_res / dev->calib_session.params.xres;
+
+    unsigned out_pixels_per_line = pixels_per_line + start_offset;
 
     dev->average_size = channels * out_pixels_per_line;
   dev->dark_average_data.clear();
@@ -1928,7 +1935,11 @@ static void genesys_dark_white_shading_calibration(Genesys_Device* dev,
 
     unsigned channels = dev->calib_session.params.channels;
 
-    unsigned out_pixels_per_line = pixels_per_line + dev->calib_session.params.startx;
+    // BUG: we are using wrong pixel number here
+    unsigned start_offset =
+            dev->calib_session.params.startx * sensor.optical_res / dev->calib_session.params.xres;
+
+    unsigned out_pixels_per_line = pixels_per_line + start_offset;
 
     dev->average_size = channels * out_pixels_per_line;
 
@@ -1989,14 +2000,14 @@ static void genesys_dark_white_shading_calibration(Genesys_Device* dev,
 
 
     std::fill(dev->dark_average_data.begin(),
-              dev->dark_average_data.begin() + dev->calib_session.params.startx * channels, 0);
+              dev->dark_average_data.begin() + start_offset * channels, 0);
     std::fill(dev->white_average_data.begin(),
-              dev->white_average_data.begin() + dev->calib_session.params.startx * channels, 0);
+              dev->white_average_data.begin() + start_offset * channels, 0);
 
     uint16_t* average_white = dev->white_average_data.data() +
-                              dev->calib_session.params.startx * channels;
+                              start_offset * channels;
     uint16_t* average_dark = dev->dark_average_data.data() +
-                             dev->calib_session.params.startx * channels;
+                             start_offset * channels;
 
   for (x = 0; x < pixels_per_line * channels; x++)
     {
@@ -2541,10 +2552,15 @@ static void genesys_send_shading_coefficient(Genesys_Device* dev, const Genesys_
   unsigned int factor;
   unsigned int coeff, target_code, words_per_color = 0;
 
+
+    // BUG: we are using wrong pixel number here
+    unsigned start_offset =
+            dev->calib_session.params.startx * sensor.optical_res / dev->calib_session.params.xres;
+
     if (dev->model->asic_type == AsicType::GL843) {
-        pixels_per_line = dev->calib_session.output_pixels + dev->calib_session.params.startx;
+        pixels_per_line = dev->calib_session.output_pixels + start_offset;
     } else {
-        pixels_per_line = dev->calib_session.params.pixels + dev->calib_session.params.startx;
+        pixels_per_line = dev->calib_session.params.pixels + start_offset;
     }
 
     unsigned channels = dev->calib_session.params.channels;
diff --git a/backend/genesys/gl124.cpp b/backend/genesys/gl124.cpp
index 095aa301f..1f37e5200 100644
--- a/backend/genesys/gl124.cpp
+++ b/backend/genesys/gl124.cpp
@@ -912,7 +912,7 @@ ScanSession CommandSetGl124::calculate_scan_session(const Genesys_Device* dev,
   /* start */
     start = static_cast<int>(dev->model->x_offset);
     start += static_cast<int>(settings.tl_x);
-    start = static_cast<int>((start * sensor.optical_res) / MM_PER_INCH);
+    start = static_cast<int>((start * settings.xres) / MM_PER_INCH);
 
     ScanSession session;
     session.params.xres = settings.xres;
@@ -1282,7 +1282,7 @@ void CommandSetGl124::init_regs_for_scan(Genesys_Device* dev, const Genesys_Sens
     start = dev->model->x_offset;
     start += dev->settings.tl_x;
     start /= sensor.get_ccd_size_divisor_for_dpi(dev->settings.xres);
-    start = static_cast<float>((start * sensor.optical_res) / MM_PER_INCH);
+    start = static_cast<float>((start * dev->settings.xres) / MM_PER_INCH);
 
     ScanSession session;
     session.params.xres = dev->settings.xres;
diff --git a/backend/genesys/gl646.cpp b/backend/genesys/gl646.cpp
index 5f1febc89..c64f5ceb2 100644
--- a/backend/genesys/gl646.cpp
+++ b/backend/genesys/gl646.cpp
@@ -1808,7 +1808,7 @@ static ScanSession setup_for_scan(Genesys_Device* dev,
             start += dev->model->x_offset_ta;
         }
     }
-    start = static_cast<float>((start * sensor.optical_res) / MM_PER_INCH);
+    start = static_cast<float>((start * settings.xres) / MM_PER_INCH);
 
     ScanSession session;
     session.params.xres = settings.xres;
@@ -3381,7 +3381,7 @@ ScanSession CommandSetGl646::calculate_scan_session(const Genesys_Device* dev,
     } else {
         start += dev->model->x_offset_ta;
     }
-    start = static_cast<float>((start * sensor.optical_res) / MM_PER_INCH);
+    start = static_cast<float>((start * settings.xres) / MM_PER_INCH);
 
     ScanSession session;
     session.params.xres = settings.xres;
diff --git a/backend/genesys/gl841.cpp b/backend/genesys/gl841.cpp
index dccf20c46..36a5a2c5c 100644
--- a/backend/genesys/gl841.cpp
+++ b/backend/genesys/gl841.cpp
@@ -1666,7 +1666,7 @@ ScanSession CommandSetGl841::calculate_scan_session(const Genesys_Device* dev,
 
     float start = dev->model->x_offset;
     start += dev->settings.tl_x;
-    start = static_cast<float>((start * sensor.optical_res) / MM_PER_INCH);
+    start = static_cast<float>((start * dev->settings.xres) / MM_PER_INCH);
 
     // we enable true gray for cis scanners only, and just when doing
     // scan since color calibration is OK for this mode
diff --git a/backend/genesys/gl843.cpp b/backend/genesys/gl843.cpp
index 4987cd3ad..06380f51b 100644
--- a/backend/genesys/gl843.cpp
+++ b/backend/genesys/gl843.cpp
@@ -1313,7 +1313,7 @@ ScanSession CommandSetGl843::calculate_scan_session(const Genesys_Device* dev,
         start /= sensor.get_ccd_size_divisor_for_dpi(settings.xres);
     }
 
-    start = static_cast<float>((start * sensor.optical_res) / MM_PER_INCH);
+    start = static_cast<float>((start * settings.xres) / MM_PER_INCH);
 
     ScanSession session;
     session.params.xres = settings.xres;
@@ -2410,7 +2410,7 @@ void CommandSetGl843::init_regs_for_warmup(Genesys_Device* dev, const Genesys_Se
     ScanSession session;
     session.params.xres = resolution;
     session.params.yres = resolution;
-    session.params.startx = num_pixels/2;
+    session.params.startx = (num_pixels / 2) * resolution / calib_sensor.optical_res;
     session.params.starty = 0;
     session.params.pixels = num_pixels;
     session.params.lines = 1;
diff --git a/backend/genesys/gl846.cpp b/backend/genesys/gl846.cpp
index b39731d66..56626ce1b 100644
--- a/backend/genesys/gl846.cpp
+++ b/backend/genesys/gl846.cpp
@@ -760,7 +760,7 @@ ScanSession CommandSetGl846::calculate_scan_session(const Genesys_Device* dev,
   /* start */
     start = static_cast<int>(dev->model->x_offset);
     start += static_cast<int>(settings.tl_x);
-    start = static_cast<int>((start * sensor.optical_res) / MM_PER_INCH);
+    start = static_cast<int>((start * settings.xres) / MM_PER_INCH);
 
     ScanSession session;
     session.params.xres = settings.xres;
@@ -1059,7 +1059,7 @@ void CommandSetGl846::init_regs_for_scan(Genesys_Device* dev, const Genesys_Sens
   /* start */
     start = dev->model->x_offset;
     start = start + dev->settings.tl_x;
-    start = static_cast<float>((start * sensor.optical_res) / MM_PER_INCH);
+    start = static_cast<float>((start * dev->settings.xres) / MM_PER_INCH);
 
     ScanSession session;
     session.params.xres = dev->settings.xres;
diff --git a/backend/genesys/gl847.cpp b/backend/genesys/gl847.cpp
index 1e2911fe5..bb11e7bc1 100644
--- a/backend/genesys/gl847.cpp
+++ b/backend/genesys/gl847.cpp
@@ -762,7 +762,7 @@ ScanSession CommandSetGl847::calculate_scan_session(const Genesys_Device* dev,
   /* start */
     start = static_cast<int>(dev->model->x_offset);
     start = static_cast<int>(start + settings.tl_x);
-    start = static_cast<int>((start * sensor.optical_res) / MM_PER_INCH);
+    start = static_cast<int>((start * settings.xres) / MM_PER_INCH);
 
     ScanSession session;
     session.params.xres = settings.xres;
@@ -1061,7 +1061,7 @@ void CommandSetGl847::init_regs_for_scan(Genesys_Device* dev, const Genesys_Sens
   /* start */
     start = dev->model->x_offset;
     start = start + dev->settings.tl_x;
-    start = static_cast<float>((start * sensor.optical_res) / MM_PER_INCH);
+    start = static_cast<float>((start * dev->settings.xres) / MM_PER_INCH);
 
     ScanSession session;
     session.params.xres = dev->settings.xres;
diff --git a/backend/genesys/low.cpp b/backend/genesys/low.cpp
index 9540ce770..98ca49baf 100644
--- a/backend/genesys/low.cpp
+++ b/backend/genesys/low.cpp
@@ -907,7 +907,7 @@ void compute_session_pixel_offsets(const Genesys_Device* dev, ScanSession& s,
         if (has_flag(s.params.flags, ScanFlag::USE_XCORRECTION) && sensor.ccd_start_xoffset > 0) {
             s.pixel_startx = sensor.ccd_start_xoffset;
         }
-        s.pixel_startx += s.params.startx;
+        s.pixel_startx += s.params.startx * sensor.optical_res / s.params.xres;
 
         if (sensor.stagger_config.stagger_at_resolution(s.params.xres, s.params.yres) > 0) {
             s.pixel_startx |= 1;
@@ -919,7 +919,9 @@ void compute_session_pixel_offsets(const Genesys_Device* dev, ScanSession& s,
         s.pixel_endx /= sensor.ccd_pixels_per_system_pixel() * s.ccd_size_divisor;
 
     } else if (dev->model->asic_type == AsicType::GL841) {
-        s.pixel_startx = ((sensor.ccd_start_xoffset + s.params.startx) * s.optical_resolution)
+        unsigned startx = s.params.startx * sensor.optical_res / s.params.xres;
+
+        s.pixel_startx = ((sensor.ccd_start_xoffset + startx) * s.optical_resolution)
                                 / sensor.optical_res;
 
         s.pixel_startx += sensor.dummy_pixel + 1;
@@ -944,8 +946,9 @@ void compute_session_pixel_offsets(const Genesys_Device* dev, ScanSession& s,
         s.pixel_endx = s.pixel_startx + s.optical_pixels;
 
     } else if (dev->model->asic_type == AsicType::GL843) {
+        unsigned startx = s.params.startx * sensor.optical_res / s.params.xres;
 
-        s.pixel_startx = (s.params.startx + sensor.dummy_pixel) / ccd_pixels_per_system_pixel;
+        s.pixel_startx = (startx + sensor.dummy_pixel) / ccd_pixels_per_system_pixel;
         s.pixel_endx = s.pixel_startx + s.optical_pixels / ccd_pixels_per_system_pixel;
 
         s.pixel_startx /= s.hwdpi_divisor;
@@ -973,7 +976,9 @@ void compute_session_pixel_offsets(const Genesys_Device* dev, ScanSession& s,
                dev->model->asic_type == AsicType::GL846 ||
                dev->model->asic_type == AsicType::GL847)
     {
-        s.pixel_startx = s.params.startx;
+        unsigned startx = s.params.startx * sensor.optical_res / s.params.xres;
+
+        s.pixel_startx = startx;
 
         if (s.num_staggered_lines > 0) {
             s.pixel_startx |= 1;
@@ -986,7 +991,9 @@ void compute_session_pixel_offsets(const Genesys_Device* dev, ScanSession& s,
         s.pixel_endx /= s.hwdpi_divisor * s.segment_count * ccd_pixels_per_system_pixel;
 
     } else if (dev->model->asic_type == AsicType::GL124) {
-        s.pixel_startx = s.params.startx;
+        unsigned startx = s.params.startx * sensor.optical_res / s.params.xres;
+
+        s.pixel_startx = startx;
 
         if (s.num_staggered_lines > 0) {
             s.pixel_startx |= 1;
@@ -1362,10 +1369,10 @@ void build_image_pipeline(Genesys_Device* dev, const Genesys_Sensor& sensor,
         !has_flag(dev->model->flags, ModelFlag::NO_CALIBRATION) &&
         !has_flag(session.params.flags, ScanFlag::DISABLE_SHADING))
     {
-        unsigned pixel_shift = session.params.startx * dev->calib_session.params.xres /
-                sensor.optical_res;
+        unsigned pixel_shift = session.params.startx;
         if (dev->model->model_id == ModelId::CANON_4400F) {
-            pixel_shift = session.params.startx;
+            pixel_shift =
+                    session.params.startx * sensor.optical_res / dev->calib_session.params.xres;
         }
         dev->pipeline.push_node<ImagePipelineNodeCalibrate>(dev->dark_average_data,
                                                             dev->white_average_data,
diff --git a/backend/genesys/settings.h b/backend/genesys/settings.h
index 0dc20707e..7bc6232b9 100644
--- a/backend/genesys/settings.h
+++ b/backend/genesys/settings.h
@@ -116,7 +116,7 @@ struct SetupParams {
     unsigned xres = NOT_SET;
     // resolution in y direction
     unsigned yres = NOT_SET;
-    // start pixel in X direction, from dummy_pixel + 1
+    // start pixel in X direction, from dummy_pixel + 1. Counted in terms of xres.
     unsigned startx = NOT_SET;
     // start pixel in Y direction, counted according to base_ydpi
     unsigned starty = NOT_SET;