How-to-save-a-chart-to-an-image-file-from-code

QUOTE:
ScottPlot library included in WL7 to render a financial chart, then save it to a file,...

ScottPlot is an excellent choice, and it's fairly easy to use. You may want to bracket your ScottPlot code in a conditional as shown below so you're not writing Charts for every stock on earth. Take note of the SaveFig(...) parameters.

Of course, you want a financial plot, not a scatter plot as shown below. https://scottplot.net/cookbook/4.1/category/plottable-finance/

CODE:
using ScottPlot;
  ...
   public override void Initialize(BarHistory bars)
    {
      ...
      if (ExecutionMode == StrategyExecutionModes.Strategy
         && ExecutionDataSetName == null) //only plot stats in single-symbol mode
      {
            Plot plt = new Plot(700, 500);
            plt.Title("Price change vs Volume for " + bars.Symbol);
            plt.XLabel("Volume");
            plt.YLabel("Price change");

            double[] xVol = new double[bars.Count], yPriceChg = new double[bars.Count];
            //Color plotColor = plt.GetNextColor();
            for (int bar = 1; bar < yPriceChg.Length; bar++)
            {
               xVol[bar] = bars.Volume[bar];
               yPriceChg[bar] = bars.Close[bar] - bars.Close[bar-1];
            }
            plt.AddScatter(xVol, yPriceChg, lineWidth: 0F);
            plt.SaveFig(Environment.GetFolderPath(Environment.SpecialFolder.Desktop) + @"\priceChgVsVolume.png");
         }
      }