I compares the previous bar's close to the current bar's high and is expressed as a percentage.
I am not much of an expert in pine so I did not program it to plot as a histogram but that is how I like to view it. If you know how, by all means, send me the edit and I will credit you.
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.