remaining med value features

tests/node_tests/local_contrast.py

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+import numpy as np
+import pytest
+from tests.node_tests._shared import make_field
+
+
+def test_local_contrast_shape_preserved():
+    from backend.nodes.local_contrast import LocalContrast
+
+    node = LocalContrast()
+    field = make_field(shape=(48, 64))
+    result, = node.process(field, kernel_size=10, weight=0.5)
+    assert result.data.shape == (48, 64)
+
+
+def test_local_contrast_weight_zero_unchanged():
+    """weight=0 blends 100% original → result equals input."""
+    from backend.nodes.local_contrast import LocalContrast
+
+    node = LocalContrast()
+    data = np.random.default_rng(0).standard_normal((32, 32))
+    field = make_field(data=data)
+    result, = node.process(field, kernel_size=5, weight=0.0)
+    assert np.allclose(result.data, data)
+
+
+def test_local_contrast_uniform_field_unchanged():
+    """A flat field has nothing to enhance; it should be returned as-is."""
+    from backend.nodes.local_contrast import LocalContrast
+
+    node = LocalContrast()
+    field = make_field(data=np.full((32, 32), 2.0))
+    result, = node.process(field, kernel_size=5, weight=1.0)
+    assert np.allclose(result.data, 2.0)
+
+
+def test_local_contrast_increases_dynamic_range():
+    """Weight=1 full enhancement should not compress global range beyond input."""
+    from backend.nodes.local_contrast import LocalContrast
+
+    rng = np.random.default_rng(1)
+    data = rng.standard_normal((64, 64))
+    field = make_field(data=data)
+    node = LocalContrast()
+    result, = node.process(field, kernel_size=8, weight=1.0)
+    # Global min/max should be preserved (by construction of the algorithm)
+    assert np.isclose(result.data.min(), data.min(), atol=1e-6)
+    assert np.isclose(result.data.max(), data.max(), atol=1e-6)
+
+
+def test_local_contrast_preserves_metadata():
+    from backend.nodes.local_contrast import LocalContrast
+
+    node = LocalContrast()
+    field = make_field()
+    result, = node.process(field, kernel_size=10, weight=0.5)
+    assert result.xreal == field.xreal
+    assert result.si_unit_z == field.si_unit_z
+
+
+def test_local_contrast_weight_clipped():
+    """Values outside [0,1] should be clipped without error."""
+    from backend.nodes.local_contrast import LocalContrast
+
+    node = LocalContrast()
+    field = make_field()
+    result, = node.process(field, kernel_size=5, weight=2.0)
+    assert result.data.shape == field.data.shape