[dr_lew]

Well, I used Paint.net to invert the "faithful" image I posted, which came out blue, then used the "hue" adjustment to get this result which resembles the APOD, but does not show the whitish "limb-darkening".

[Telepathic Intruder]

Actually I can see that it’s slightly darker in the center than at the edges. This is what you’d expect to see . The darkening actually occurs because the edges are scattered by more solar atmosphere, even though you can’t see the atmosphere itself in that wavelength.