init commit

python_app/gui/plotting/bscan_math.py

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+"""Color-scaling helpers for B-scan visualization."""
+
+from __future__ import annotations
+
+import numpy as np
+import pyqtgraph as pg
+
+def bscan_lookup_table(axis_mode: str) -> np.ndarray:
+    """Build B-scan colormap table for selected axis mode."""
+    if axis_mode == "abs":
+        return build_lut(["#440154", "#31688e", "#35b779", "#fde725"])
+    return build_lut(["#2166ac", "#67a9cf", "#f7f7f7", "#ef8a62", "#b2182b"])
+
+
+def build_lut(stops: list[str], *, size: int = 256) -> np.ndarray:
+    """Interpolate hex color stops into 8-bit RGB LUT array."""
+    stop_positions = np.linspace(0.0, 1.0, num=len(stops), dtype=np.float32)
+    sample_positions = np.linspace(0.0, 1.0, num=size, dtype=np.float32)
+    stop_colors = np.asarray([pg.mkColor(value).getRgb()[:3] for value in stops], dtype=np.float32)
+
+    lut = np.empty((size, 3), dtype=np.uint8)
+    for channel in range(3):
+        lut[:, channel] = np.interp(sample_positions, stop_positions, stop_colors[:, channel]).astype(np.uint8)
+    return lut
+
+
+def bscan_levels(sweeps: np.ndarray, axis_mode: str) -> tuple[float, float]:
+    """Compute image levels for B-scan data based on axis mode."""
+    min_value = float(np.min(sweeps))
+    max_value = float(np.max(sweeps))
+    if axis_mode == "abs":
+        if max_value <= min_value:
+            return min_value, min_value + 1e-6
+        return min_value, max_value
+
+    max_abs = max(abs(min_value), abs(max_value), 1e-6)
+    return -max_abs, max_abs