Interactive figures are generated on users’ browser and their default resolution is related to their screen resolution. On my retina display, the default resolution for a screenshot is 150 DPI
Keep in mind that DPI is defined as dot per inch - 150 dpi means 150 pixel / inch. There will be 1200 pixels for a 8 inch width figure. If you scale the image width to 4 inch, the resolution will be 1200/4 = 300 dpi.
Note since interactive graphics allow “zoom in”, you can create any high-resolution images. If your screen resolution is very low, you may need to carefully piece together the screenshots of different regions
For image manipuation, we recommend GIMP or InkScape