Linearity plots for the optical parameters of the MEDPHOT phantoms at 830 nm.
Full markers represent the values measured for an inter-fiber distance ρ = 1.5
cm, hollow markers are for ρ = 2.5 cm. Error bars represent standard deviations
over 10 repetitions. 
Fig4a: Measured absorption vs. conventional absorption
Fig4b: Measured scattering vs. conventional absorption
Fig4c: Measured absorption vs. conventional scattering
Fig4d: Measured scattering vs. conventional scattering.
Different colors represent different scattering (Fig4a and Fig4b) or absorption
(Fig4c and Fig4d) series.
Figures 4a and 4d also show 1:1 lines (solid) and ±3% lines (dashed).

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Column names syntax:
<tag>_<OP>_<rho>_<series>[_err]

<tag> can either be conv or meas:
- conv means that the column reports the conventionally true values for a
phantom, i.e. the values measured with a validated instrument.
- meas means that the column reports the values that were measured with the
device presented in the article.

<OP> can either be mua (absorption coefficient) or mus (reduced scattering
coefficient), both expressed in cm^(-1)

<rho> can either be 15 or 25, and is the source-detector separation in mm.

<series> can either be a letter from A to B or a number from 1 to 8:
- if it is a letter, it indicates the scattering series of the MEDPHOT phantom
- if it is a number, it indicates the absorption series of the MEDPHOT phantom
For further information, see the original MEDPHOT paper:
[Pifferi2005] A. Pifferi et al., Performance assessment of photon migration
instruments: the MEDPHOT protocol, doi: 10.1364/AO.44.002104

If _err is not present, then it means that the values in the column refer to
the mean value measured. If _err is present, then the values in the column are
the standard deviation of the measurements, reported as error bars in the
scatterplots.


Example 1: the column labeled "conv_mua_15_B" contains the conventionally
true values of the absorption coefficients expressed in cm^(-1) measured
with a source-detector separation of 15 mm on the MEDPHOT phantoms belonging
to the B scattering series.

Example 2: the column labeled "meas_mus_25_4_err" contains the errors on the
values of the reduced scattering coefficients expressed in cm^(-1) measured
with a source-detector separation of 25 mm on the MEDPHOT phantoms belonging
to absorption series 4.
