Below is a screenshot of this new chart version, of today's (Friday's) price action at a 10 minute bar scale:
The first change is in how the volume profile (the horizontal histogram on the left) is calculated. The "old" version of the chart calculates the profile by assuming the "model" that tick volume for each 10 minute bar is normally distributed across the high/low range of the bar, and then the profile histogram is the accumulation of these individual, 10 minute, normally distributed "mini profiles." A more complete description of this is given in my Market Profile Chart in Octave blog post, with code.
The new approach is more data centric rather than model based. Every 10 minutes, instead of downloading the 10 minute OHLC and tick volume, the last 10 minutes worth of 5 second OHLC and tick volume is downloaded. The whole tick volume of each 5 second period is assigned to a price level equivalent to the Typical price (rounded to the nearest pip) of said 5 second period, and the volume profile is then the accumulation of these volume ticks per price level. I think this is a much more accurate reflection of the price levels at which tick volume actually occurred compared to the old, model based charts. This second screenshot is of the old chart over the exact same price data as the first, improved version of the chart.Low Volume Nodes).
The second change in the new chart is in how the background heatmap is plotted. The heatmap is a different presentation of the volume profile whereby higher volume price levels are shown by the brighter yellow colours. The old chart only displays the heatmap associated with the latest calculated volume profile histogram, which is projected back in time. This is, of course, a form of lookahead bias when plotting past prices over the latest heatmap. The new chart solves this by plotting a "rolling" version of the heatmap which reflects the volume profile that was in force at the time each 10 minute OHLC candle formed. It is easy to see how the Points of Control and Low Volume Nodes price levels ebb and flow throughout the trading day.
The third change, which naturally followed on from the downloading of 5 second data, is in the plotting of the candlesticks. Rather than having a normal, open to close candlestick body, the candlesticks show the "mini volume profiles" of the tick volume within each bar, plotted via Octave's patch function. The white candlestick wicks indicate the usual high/low range, and the open and close levels are shown by grey and black dots respectively. This is more clearly seen in the zoomed in screenshot below.