The 'Grain Equalization' parameter lets the user reintroduce removed noise grain in a modified, uniform way, that is; appearing of equal magnitude across the image (rather than being highly dependent per-pixel signal strength, stretches and local enhancements as seen in the input image).
The 'Grain Equalization' feature an acknowledgement of the "two schools" of noise reduction prevalent in astrophotography; there are those who like smooth images with little to no noise grain visible, and there are those who find a tightly controlled, uniform measure of noise grain desirable for the purpose of creating visual interest and general aesthetics (much like noise grain is added for a "filmic" look in CGI). The noise signature of the deliberately left-in noise, is precisely shaped to be aesthetically pleasing for precisely this purpose.
Lastly, it should be noted that the 'Grain Equalization' feature only shapes and re-introduces noise in the luminance portion of the signal, but not in the chrominance (color) portion of the signal.
In StarTools, your signal is processed (read and written) in a time-fluid way, by means of an ever changing equation for every pixel.
Exclusive to the main screen, the buttons that activate the different modules, reside on the left hand side of the main screen.
Whatever detail lies outside the RoI, is simply forced to conform to the stretch that was designed for the RoI.
Open an image stack ("dataset"), fresh from a stacker.
Nevertheless the result can look quite pleasing when simply browsing past the image in a Facebook feed.
You can convert everything you see to a format you find convenient. Give it a try!