The idea is simple, highest only gets calculated for green candles, lowest only gets calculated for red candles. a yellow dot gets created when a candle gets below lowest line and closes , vise versa for red dots.
Hope someone can use it.
In true TradingView spirit, the author of this script has published it open-source, so traders can understand and verify it. Cheers to the author! You may use it for free, but reuse of this code in a publication is governed by House Rules. You can favorite it to use it on a chart.