Add Mueller matrix normalization guidance: README.md

README.md

@@ -152,6 +152,13 @@ channel name is normalized to `eta`.
 
 ## Physical Parameter Definitions
 
+Mueller matrix elements are generally expected to lie within `[-1, 1]` after
+normalization. In measured data, small deviations outside this range may occur
+because of acquisition noise, calibration differences, numerical processing, or
+normalization error. Users should inspect the value distribution for their split
+and apply task-appropriate preprocessing before training, such as clipping,
+standardization, or normalization based on the training set.
+
 The target tensor follows this channel order and nominal parameter range:
 
 ```text
@@ -165,6 +172,8 @@ Important encoding note:
 - Waveplate target arrays are stored from the source `.npy` files as float32.
 - Spectral target arrays were converted from grayscale PNG files to float32
   values normalized to `[0, 1]`; see `target_encoding`.
+- Mueller matrix tensors are stored as measured/processed values, not forcibly
+  clipped to `[-1, 1]`.
 
 ## Reference Label Generation
 
@@ -260,6 +269,11 @@ The targets are Lu-Chipman reference outputs. Evaluation should be interpreted
 as agreement with a physics-solver reference and related physics consistency,
 not as proof of absolute biological ground truth.
 
+Measured Mueller matrix entries may be slightly outside the nominal `[-1, 1]`
+range. This is expected for real acquisition pipelines; users should decide
+whether to clip, standardize, or otherwise normalize values according to their
+training protocol.
+
 ## License
 
 This dataset is released under CC BY-NC 4.0.