OPI (version 2.1)

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

Description

Given a value in cd/$\mbox{m}^2$, return the dB equivalent. The default is HFA dB scale (maxumum stimulus 10000 apostilbs).

Usage

cdTodb(cd, maxStim=10000/pi)

Arguments

cd

Value to convert in cd/$\mbox{m}^2$

maxStim

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

Value

• Returns dB 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

dbTocd

Examples

dB <- cdTodb(10000/pi)  # 0 dB
    dB <- cdTodb(1000/pi)   # 10 dB
    dB <- cdTodb(100/pi)    # 20 dB
    dB <- cdTodb(10/pi)     # 30 dB
    dB <- cdTodb(1/pi)      # 40 dB
    dB <- cdTodb(0.1/pi)    # 50 dB