Yes, it is the Neowise comet and the processing was done with 9. If anybody hasn't seen it yet, hope for a clear night and take a look tonight, looking toward the northwest about 45 degrees up from the horizon, as very soon (couple of days) it will fade too much to be seen without binoculars or a scope.
Attached is an .mxb project with the image and various colorizations.
How it was done:
1. Import the original photo (comet3 in the project). That photo looks like a grayscale image, but it is really an RGB image.
2. Copy and paste the image (not the table, just the image), so now you can open that copy and change the Style.
3. Style that image using channel 0 or 1 or 2, with the desired number of breaks, a palette, and choosing equal intervals, equal count, and interpolate or some other method. Applying hill shading or not.
The project has a bunch of different images using different Style arrangements. Note that those don't add anything to the size of the project since they all are basically styling the same data, only one copy of which is in the table that all the images use.
There are all kinds of things you can do with Manifold to manipulate photo images, to bring out different sorts of detail, etc. For example, you could use matrix filters, or create an image with just one channel and then do curvature enhancement on it, do contours, etc.
The particular example isn't anything scientific, it just looks cool.