Merge pull request #8711 from ArkadiuszRaj:aravis_autoexposure_correction

Aravis: Use of std::fabs, added support for 16-bit mono files and exposure compensation (#8711)

* Use of std::fabs, added support for 16-bit mono files

* Correction in priority2 stage &  adding exposure compensation

modules/videoio/src/cap_aravis.cpp

@@ -64,6 +64,7 @@
 //  read/write
 //      CAP_PROP_AUTO_EXPOSURE(0|1)
 //      CAP_PROP_EXPOSURE(t), t in seconds
+//      CAP_PROP_BRIGHTNESS (ev), exposure compensation in EV for auto exposure algorithm
 //      CAP_PROP_GAIN(g), g >=0 or -1 for automatic control if CAP_PROP_AUTO_EXPOSURE is true
 //      CAP_PROP_FPS(f)
 //      CAP_PROP_FOURCC(type)
@@ -77,11 +78,13 @@
 //      video/x-raw, fourcc:'GREY'  -> 8bit, 1 channel
 //      video/x-raw, fourcc:'Y800'  -> 8bit, 1 channel
 //      video/x-raw, fourcc:'Y12 '  -> 12bit, 1 channel
+//      video/x-raw, fourcc:'Y16 '  -> 16bit, 1 channel
 //
 
 #define MODE_GREY   CV_FOURCC_MACRO('G','R','E','Y')
 #define MODE_Y800   CV_FOURCC_MACRO('Y','8','0','0')
 #define MODE_Y12    CV_FOURCC_MACRO('Y','1','2',' ')
+#define MODE_Y16    CV_FOURCC_MACRO('Y','1','6',' ')
 
 #define CLIP(a,b,c) (cv::max(cv::min((a),(c)),(b)))
 
@@ -139,6 +142,7 @@ protected:
     double          exposureMax;            // Camera's maximum exposure time.
 
     bool            controlExposure;        // Flag if automatic exposure shall be done by this SW
+    double          exposureCompensation;
     bool            autoGain;
     double          targetGrey;             // Target grey value (mid grey))
 
@@ -179,10 +183,11 @@ CvCaptureCAM_Aravis::CvCaptureCAM_Aravis()
     xoffset = yoffset = width = height = 0;
     fpsMin = fpsMax = gainMin = gainMax = exposureMin = exposureMax = 0;
     controlExposure = false;
+    exposureCompensation = 0;
     targetGrey = 0;
     frameID = prevFrameID = 0;
 
-    num_buffers = 50;
+    num_buffers = 10;
     frame = NULL;
 }
 
@@ -314,6 +319,7 @@ IplImage* CvCaptureCAM_Aravis::retrieveFrame(int)
                 channels = 1;
                 break;
             case ARV_PIXEL_FORMAT_MONO_12:
+            case ARV_PIXEL_FORMAT_MONO_16:
                 depth = IPL_DEPTH_16U;
                 channels = 1;
                 break;
@@ -334,8 +340,8 @@ IplImage* CvCaptureCAM_Aravis::retrieveFrame(int)
             }
             cvCopy(&src, frame);
 
-            if(controlExposure && ((frameID - prevFrameID) > 1)) {
-                // control exposure every second frame
+            if(controlExposure && ((frameID - prevFrameID) >= 3)) {
+                // control exposure every third frame
                 // i.e. skip frame taken with previous exposure setup
                 autoExposureControl(frame);
             }
@@ -372,15 +378,15 @@ void CvCaptureCAM_Aravis::autoExposureControl(IplImage* image)
     midGrey = brightness;
 
     double maxe = 1e6 / fps;
-    double ne = CLIP( ( exposure * d ) / dmid, exposureMin, maxe);
+    double ne = CLIP( ( exposure * d ) / ( dmid * pow(sqrt(2), -2 * exposureCompensation) ), exposureMin, maxe);
 
     // if change of value requires intervention
-    if(fabs(d-dmid) > 5) {
+    if(std::fabs(d-dmid) > 5) {
         double ev, ng = 0;
 
         if(gainAvailable && autoGain) {
             ev = log( d / dmid ) / log(2);
-            ng = CLIP( gain + ev, gainMin, gainMax);
+            ng = CLIP( gain + ev + exposureCompensation, gainMin, gainMax);
 
             if( ng < gain ) {
                 // piority 1 - reduce gain
@@ -390,8 +396,9 @@ void CvCaptureCAM_Aravis::autoExposureControl(IplImage* image)
         }
 
         if(exposureAvailable) {
-            if(abs(exposure - ne) > 2) {
-                // priority 2 - control of exposure time
+            // priority 2 - control of exposure time
+            if(std::fabs(exposure - ne) > 2) {
+                // we have not yet reach the max-e level
                 arv_camera_set_exposure_time(camera, (exposure = ne) );
                 return;
             }
@@ -436,6 +443,9 @@ double CvCaptureCAM_Aravis::getProperty( int property_id ) const
         case CV_CAP_PROP_AUTO_EXPOSURE:
             return (controlExposure ? 1 : 0);
 
+    case CV_CAP_PROP_BRIGHTNESS:
+        return exposureCompensation;
+
         case CV_CAP_PROP_EXPOSURE:
             if(exposureAvailable) {
                 /* exposure time in seconds, like 1/100 s */
@@ -463,6 +473,8 @@ double CvCaptureCAM_Aravis::getProperty( int property_id ) const
                         return MODE_Y800;
                     case ARV_PIXEL_FORMAT_MONO_12:
                         return MODE_Y12;
+                    case ARV_PIXEL_FORMAT_MONO_16:
+                        return MODE_Y16;
                 }
             }
             break;
@@ -490,6 +502,9 @@ bool CvCaptureCAM_Aravis::setProperty( int property_id, double value )
                 }
             }
             break;
+    case CV_CAP_PROP_BRIGHTNESS:
+       exposureCompensation = CLIP(value, -3., 3.);
+       break;
 
         case CV_CAP_PROP_EXPOSURE:
             if(exposureAvailable) {
@@ -528,6 +543,10 @@ bool CvCaptureCAM_Aravis::setProperty( int property_id, double value )
                         newFormat = ARV_PIXEL_FORMAT_MONO_12;
                         targetGrey = 2048;
                         break;
+                    case MODE_Y16:
+                        newFormat = ARV_PIXEL_FORMAT_MONO_16;
+                        targetGrey = 32768;
+                        break;
                 }
                 if(newFormat != pixelFormat) {
                     stopCapture();
@@ -570,7 +589,6 @@ bool CvCaptureCAM_Aravis::startCapture()
 {
     if(init_buffers() ) {
         arv_camera_set_acquisition_mode(camera, ARV_ACQUISITION_MODE_CONTINUOUS);
-        arv_device_set_string_feature_value(arv_camera_get_device (camera), "TriggerMode" , "Off");
         arv_camera_start_acquisition(camera);
 
         return true;