 DarkLight
Bollinger Bands (BB)
 DarkLight
Bollinger Bands (BB) is a technical analysis tool that helps monitor price volatility. BB plots a Simple Moving Average (SMA) and two standard deviations above and below the SMA as overbought and oversold levels. The greater the price deviation from the moving average, the higher the volatility.
MidLine = SMA_{n} (TP)
LowerBand = MidLine  (σTP_{n} x m)
UpperBand = MidLine + (σTP_{n} x m)
where:
SMA_{ }– Simple Moving Average for the period
_{}TP – Typical Price
σTP_{n} – Standard Deviation over last n periods of TP
_{}m – the multiplier_{}
n – the number of periods
INPUTS
Input  Description 

Length  The number of periods the indicator uses to calculate the MidLine 
Displace  The number of bars the indicator to be shifted to 
NumDevDown  The standard deviation value (in points) to plot the LowerBand 
NumDevUp  The standard deviation value (in points) to plot the UpperBand 
Price 

The following data sources are available for calculation of MidLine:

Average 

The following Moving Average types are available for calculations:

PLOTS
The plot renders the data you are working with on the chart. You can show/hide a plot by clicking the corresponding item in the settings. Every plot has a set of basic settings that you can change: color, weight, and type.
Plot  Description 

LowerBand  The lower deviation from the MidLine 
MidLine  The middle line 
UpperBand  The upper deviation from the MidLine 
Color 

Click the color rectangle under the plot's name to open the palette. Use the slider at the bottom to set the opacity of the color. To create a custom color:
The customcreated colors are added to your palette. To remove a custom color, drag it out of the palette. 
Weight 
Change the value (in px) to adjust the thickness of the plot. 
Type 
The following plot types are available:

OVERLAYING
Check Overlaying to display the indicator on the chart. Otherwise, the indicator is shown in a study pane down below.