Well, Here's an oddity

With all the cloudy weather, I decided to look at some other astronomer's blogs to see if I could glean some information on image processing. I think I hit the jackpot on Jerry Lodriguss's site Catching the Light. Specifically, this link http://www.astropix.com/HTML/J_DIGIT/VIGNET.HTM about uneven field illumination. Look back to an entry around April 10^th 2016 at the images and problems with the galaxy M100. Here's the problem image.

M100. Notice the light area extending into the corners.

As you can see, the field (or basically the image) is not evenly dark. There looks to be a bright bulls eye or circle near the edges. By using the ideas in Jerry's article, I was able to remove most, but not all, of the offending bright circle.

Same image as above, but with a lot of the brightness near the corners removed.

Now I think you can see that most of it is gone. I think that looks better, don't you? It shows a little less of the galaxy, but I think the general improvement is worth it. Nevertheless, I still think the best of the bunch is the one that's the luminescence channel only.

Still the best of the bunch. Black and white only image.

Oh, and the oddity? I wrote an entry without taking ANY images! Just recycled an old one.