densities = PhotopigmentAxialDensity(receptorTypes,[species],[source],[fieldSizeDegrees])

Return estimates of photopigment axial density, sometimes called peak

Allowable receptor types depend on species and source, but the general
list is:
SCone, MCone, LCone, FovealSCone, FovealMCone, FovealLCone, Rod.

The type argument may be a single string or a cell array of strings. If it
is an array, a column vector of values is returned.

The foveal version of cone types is sensible only for primates. Not all
estimate sources support all receptor types.

Note that the following three numbers are overdetermined: photopigment
specific density (sd), photopigment axial density (ad), and outer segment
length osl. In particular, ad = sd*osl. Depending on the measurement
method, different sources provide different pairs of these numbers.
We have attempted to enforce this consistency in the set of routines
PhotopigmentSpecificDensity, PhotopigmentAxialDensity, and PhotoreceptorDimensions.
That is to say, for the same source, species, and cone type, you should get
a consistent triplet of numbers.

Supported species:
Human (Default).

Supported sources:
Rodieck (Human) (Default).
StockmanSharpe (Human).
CIE (Human).
Tsujimura (Human; melanopsin-containing RGCs))

The CIE method takes a field size argument. This
overrides the specified foveal or not part of the
cone string. If the field type is not passed and
the method is CIE, it is set to 10-degrees for SCone, MCone,
and LcCne, and to 2-degrees for FovealSCone, FovealMCone, and

The fieldSizeDegrees argument is ignored for sources other than

7/11/03 dhb Wrote it.
8/12/11 dhb Added CIE source, and allow passing of fieldSizeDegrees.
4/20/12 dhb Add Tsujimura’s estimate of melanopsin optical density in human.
12/16/12 dhb, ms Add Alpern’s rod estimates from CVRL table.

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