If you would like to save charts from application as image, press the "Save chart as image..." button (See below. It also works for comparison view.)
A window appears where you can configure the details of saving as image:
You can modify the size of the image as you like. Charts in the image file will not be pixelated even when resolution is high because the chart is re-rendered for each size. (You may print eg.: an A3 size poster from the charts)
When you are done with settings you can save the image file by pressing the "Save" or "Save as..." button.