This strategy utilize Heikin-Ashi candlestick chart.
Heikin-Ashi technique is a Japanese candlestick-based technical trading tool that uses candlestick charts to represent and visualize market price data.
Heikin-Ashi candle is essentially taking an average of the movement.
There is a tendency with Heikin-Ashi for the candles to stay red during a downtrend and...
You can use this script to backtest Heikin-Ashi bar color change strategy.
You have to apply this script to usual candles and not Heikin-Ashi!!!
Background color indicates HA bar color. On change you'll see green/red arrows and alert will be fired.
Also you can find in the code calculations of all HA OHLC values.