cdTodb {OPI}

Convert cd/\mbox{m}^2 to perimetric dB.

Description

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

Usage

cdTodb(cd, maxStim = 10000/pi)

Arguments

cd

Value to convert to dB in cd/\mbox{m}^2. Must be > 0.

maxStim

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

Value

A dB value for cd cd/\mbox{m}^2.

Examples

# candela to decibels
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