OPI (version 2.1)

dbTocd: Convert dB to cd/$\mbox{m}^2$.

Description

Given a value in dB, return the cd/$\mbox{m}^2$ equivalent. Default is to use HFA units, so maximum stimulus is 10000 apostilbs.

Usage

dbTocd(db, maxStim=10000/pi)

Arguments

db

Value to convert to dB

maxStim

Stimulus value for 0dB in cd/$\mbox{m}^2$

Value

• Returns cd/$\mbox{m}^2$ value.

References

Please cite: A. Turpin, P.H. Artes and A.M. McKendrick "The Open Perimetry Interface: An enabling tool for clinical visual psychophysics", Journal of Vision 12(11) 2012.

http://perimetry.org/OPI

See Also

cdTodb

Examples

cd <- dbTocd(0)   # 10000/pi
    cd <- dbTocd(10)  # 1000/pi
    cd <- dbTocd(20)  # 100/pi
    cd <- dbTocd(30)  # 10/pi
    cd <- dbTocd(40)  # 1/pi