Real author:
Forex-TSD.com
The indicator changes color of bars in a separate window. It is changed to the color of the current trend calculated based on the RSI technical indicator.
If the trend and candlestick direction match, the color of the bar is light, if opposite, the bar is dark.
Trend strength is determined by the presence of the RSI indicator in overbought or oversold areas whose levels are determined by the indicator input parameters:
input uint  HighLevel=55;   // Overbought level input uint  LowLevel=45;    // Oversold level
If the RSI is outside these areas, the bar is painted in light gray.
Figure 1. The RSIFilter indicator