pp_from_absorbance — Absorbance-to-reflectance/transmittance conversion¶
Group: Preprocessing · C ABI: n4m_transform_from_absorbance_*
Description¶
R = 10**(-A), optionally returned as percent.
Parameters¶
Name |
Type |
Default |
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API and bindings¶
C ABI (ABI 2): n4m_transform_from_absorbance_create · n4m_transform_from_absorbance_destroy · n4m_transform_from_absorbance_transform. Use the linked public header for the exact signature, configuration, and result handles.
Python (verified public re-export):
from n4m.transform.signal_conversion import FromAbsorbance
Source signature: FromAbsorbance(is_percent: bool = False).
R: no current source-verified entry point was found for this catalog method.
MATLAB / Octave: no current source-verified entry point was found for this catalog method.
Explanations¶
Bibliographic source¶
Beer (1852), Bestimmung der Absorption des rothen Lichts in farbigen Flüssigkeiten, Annalen der Physik 162, 78–88, https://doi.org/10.1002/andp.18521620505.
Mathematical principle¶
The inverse base-10 absorbance relation is applied element-wise: \(R=10^{-A}\) (or \(T=10^{-A}\)). With is_percent, the result is additionally multiplied by 100.
Appropriate uses¶
Returning log-transformed spectra to fractional or percent reflectance/transmittance units.
Limits and validation¶
The formula cannot distinguish reflectance from transmittance and assumes base-10 absorbance. Large negative or positive values can overflow or underflow.
Implementation¶
n4m.transform.signal_conversion.FromAbsorbance wraps n4m_transform_from_absorbance_*; the power transform is in signal_conversion/from_absorbance.c.
The ABI-2 implementation is the n4m_transform_from_absorbance_* lifecycle in libn4m.
Sources and provenance¶
https://doi.org/10.1002/andp.18521620505; https://github.com/GBeurier/nirs4all-methods/blob/main/cpp/src/core/preprocessing/signal_conversion/from_absorbance.c
See also: methods index · interactive dashboard