check background

rfg_adc_plotter/gui/pyqtgraph_backend.py

@@ -170,6 +170,30 @@ def resolve_visible_aux_curves(aux_curves: SweepAuxCurves, enabled: bool) -> Swe
     return aux_1_arr, aux_2_arr
 
 
+def compute_background_subtracted_bscan_levels(
+    disp_fft_lin: np.ndarray,
+    disp_fft: np.ndarray,
+) -> Optional[Tuple[float, float]]:
+    """Pick robust color levels from positive residuals after background subtraction."""
+    if disp_fft_lin.size == 0 or disp_fft.size == 0:
+        return None
+    positive_mask = np.isfinite(disp_fft_lin) & (disp_fft_lin > 0.0)
+    if np.count_nonzero(positive_mask) < 2:
+        return None
+    vals = np.asarray(disp_fft[positive_mask], dtype=np.float64).reshape(-1)
+    vals = vals[np.isfinite(vals)]
+    if vals.size < 2:
+        return None
+    try:
+        vmin = float(np.nanpercentile(vals, 15.0))
+        vmax = float(np.nanpercentile(vals, 99.7))
+    except Exception:
+        return None
+    if not (np.isfinite(vmin) and np.isfinite(vmax)) or vmin >= vmax:
+        return None
+    return (vmin, vmax)
+
+
 def run_pyqtgraph(args) -> None:
     """Start the PyQtGraph GUI."""
     peak_calibrate_mode = bool(getattr(args, "calibrate", False))
@@ -1330,15 +1354,8 @@ def run_pyqtgraph(args) -> None:
 
             levels = None
             if active_background is not None:
-                try:
-                    p5 = float(np.nanpercentile(disp_fft, 5))
-                    p95 = float(np.nanpercentile(disp_fft, 95))
-                    span = max(abs(p5), abs(p95))
-                    if np.isfinite(span) and span > 0.0:
-                        levels = (-span, span)
-                except Exception:
-                    levels = None
-            else:
+                levels = compute_background_subtracted_bscan_levels(disp_fft_lin, disp_fft)
+            if levels is None:
                 try:
                     mean_spec = np.nanmean(disp_fft, axis=1)
                     vmin_v = float(np.nanmin(mean_spec))