In May 2015 I said,

In addition to piping, high pass filters cause data loss by blowing pixels.
That's what is unrecoverable to the extent that it occurs.

I hope I was wrong to an extent that help is possible.

-- I downloaded a free-for-mod model for a new Shirley, partly because it came as a 4:4:4 TIFF (I made sure it wasn't a pretender) making it an ideal 8 bit reference. It's easy to see that our 21st c. artiste pushed creative license a little past the physical confines of 8 bit reality.

So, I can fix individual blown pixels in Photoshop, I can tame the lower curve to a small extent, is there a particular convolution matrix I can test to deconstruct the gain and grain, or a premade filter. perhaps?

(Actually, I'm playing with the Convolution Blur preset right now, after having abandoned it on a previous project.) A guy over at Handbrake wrote an incredibly slow NLMeans filter with which I've had little success regarding grain in post..

Anyone care to take a crack at it? (Where are ye Grazie?)