camerad: ev scaling (#34070)

ev scaling

Co-authored-by: Waddle Wednesday <>

system/camerad/cameras/camera_qcom2.cc

@@ -140,14 +140,14 @@ void CameraState::set_camera_exposure(float grey_frac) {
   // Therefore we use the target EV from 3 frames ago, the grey fraction that was just measured was the result of that control action.
   // TODO: Lower latency to 2 frames, by using the histogram outputted by the sensor we can do AE before the debayering is complete
 
-  const float cur_ev_ = cur_ev[camera.buf.cur_frame_data.frame_id % 3];
   const auto &sensor = camera.sensor;
+  const float cur_ev_ = cur_ev[camera.buf.cur_frame_data.frame_id % 3] * sensor->ev_scale;
 
   // Scale target grey between 0.1 and 0.4 depending on lighting conditions
   float new_target_grey = std::clamp(0.4 - 0.3 * log2(1.0 + sensor->target_grey_factor*cur_ev_) / log2(6000.0), 0.1, 0.4);
   float target_grey = (1.0 - k_grey) * target_grey_fraction + k_grey * new_target_grey;
 
-  float desired_ev = std::clamp(cur_ev_ * target_grey / grey_frac, sensor->min_ev, sensor->max_ev);
+  float desired_ev = std::clamp(cur_ev_ / sensor->ev_scale * target_grey / grey_frac, sensor->min_ev, sensor->max_ev);
   float k = (1.0 - k_ev) / 3.0;
   desired_ev = (k * cur_ev[0]) + (k * cur_ev[1]) + (k * cur_ev[2]) + (k_ev * desired_ev);
 

system/camerad/sensors/os04c10.cc

@@ -43,6 +43,7 @@ OS04C10::OS04C10() {
   frame_data_type = 0x2c;
   mclk_frequency = 24000000; // Hz
 
+  ev_scale = 150.0;
   dc_gain_factor = 1;
   dc_gain_min_weight = 1;  // always on is fine
   dc_gain_max_weight = 1;
@@ -59,7 +60,7 @@ OS04C10::OS04C10() {
   for (int i = 0; i <= analog_gain_max_idx; i++) {
     sensor_analog_gains[i] = sensor_analog_gains_OS04C10[i];
   }
-  min_ev = (exposure_time_min) * sensor_analog_gains[analog_gain_min_idx];
+  min_ev = exposure_time_min * sensor_analog_gains[analog_gain_min_idx];
   max_ev = exposure_time_max * dc_gain_factor * sensor_analog_gains[analog_gain_max_idx];
   target_grey_factor = 0.01;
 

system/camerad/sensors/sensor.h

@@ -43,6 +43,7 @@ public:
   float dc_gain_on_grey;
   float dc_gain_off_grey;
 
+  float ev_scale = 1.0;
   float sensor_analog_gains[ANALOG_GAIN_MAX_CNT];
   int analog_gain_min_idx;
   int analog_gain_max_idx;