I had some more fun with Mars, discovering some decent data from 27th September 2020 that I hadn’t previously processed. Revision C is the one I did process from that run, with a timestamp of 17:00UT. In that image (Revision C), Elysium Mons, the extinct volcano is at the Central Meridian to the north (up). It is the slightly ruddy protuberance, surrounded by a lighter coloured plain. Sinus Gomer is to the south, below it in the image, like two fingers of dark paint dripping upwards.

The main image is one I just processed from an earlier run that night at 14:43UT. Notice the beautiful white cloud around the Tharsis Shield Volcanoes at the terminator, with Olympus Mons bulging prominently to their north. On the other limb at about the same latitude is Elysium Mons, which was rotating into view, to be central as seen in the Revision C image 2+ hours later.

I did some work to mitigate the Mars Edge Rind Effect using WinJUPOS and Photoshop as described below. 

Using the mouse over (Revision E) you can readily see the Mars Edge Rind Effect at the lower left limb as the dark ring inside it. This is a diffraction effect, where there is a sudden change from light to dark. It is real and optical in nature, and therefore hard to get rid of. It does spoil many if not most images of Mars. 

I had wondered if, using the derotation function in WinJUPOS, I could rotate the later image (Revision C) to the same timestamp of the earlier image. I was indeed able to rotate the 17:00UT image to the time stamp of the main image 14:43UT. The result is shown as Revision D. Since the edge here was rotated from the later image, where there was no such edge effect, the limb is clean and the detail goes right to the edge.

I brought this into a layer in Photoshop, under the 14:43UT image with the Edge Rind Effect (Revision E) and was able to replace the edge rind affected area with the clean limb. The only problem was that near the limb there are blue-white clouds, which show up when edge on, but not so much when we are looking perpendicularly through them at the more central longitudes of the planet. I had to do some work to match colours and brightness, to retain the blue-white hue clearly present at the limb, due to these clouds. This did complicate things, and is the reason some of the effect remains since  I had to feather in the new area quite a bit so it blended seamlessly. So yes there is still a touch of the diffraction effect but pleasingly it is vastly reduced. I hope you’ll agree.

The mouse-over allows you to see how well the effect has been mitigated.

Perhaps you found this of interest and potentially of use for 2022.