Robust NDWI Calculation with Edge-Protected Gaussian Filteringprotected blurring#73
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This PR improves the numerical stability and spatial accuracy of the NDWI labeling process.
Numerical Stability - Implemented np.nan_to_num and np.errstate to handle zero-division and invalid pixels (0/0 cases) safely, which is critical for raw satellite sensor data.
Edge Protection - ntroduced a NoData mask ($green == 0$ ) that is applied after Gaussian blurring. This prevents the "smearing" of zero-value border pixels into the valid NDWI data, preserving the coastline's integrity at the image boundaries.
Value Distinction - Mapped NoData values to -1.0 to clearly distinguish "No Information" from "Deep Water" (NDWI \approx 1.0) and "Land" (NDWI < 0).