I don't know what the difference in processing is between your image and the one on the first page, but there are darker areas in the two left quadrants which suggest its not just glow. It also looks a bit big compared to the glow on the ends of other lines.
Your observation represents our problem very well indeed.
It's a very crude and inaccurate method rendering images this way. Which illustrates the point I'm trying to make.
- Be careful what you interpret based on someone renderings.
We don't know the parameters required for rendering it picture perfectly, and all current renderings are based on assumptions.
Eggshapes, ovals, circles, with background noise, without background noise - all depends on the parameters being applied in the proprietary software Audacity.