Am I dreaming, or do I recall reading something about being able to "save a color table" or "save color transformations" or somesuch, which has the effect of "canning" all old-to-new colors no matter how they were created in Photoshop, in various steps in destructive editing. This can then be applied to another similar image to redo the total of the changes.
This is not related to saving presets of some adjustment layer: I know about those, and it's not what I'm asking.
In this case, I used a (destructive) filter, and eventually saved the file. I also have a copy of the original, so I can look at the difference between them. The description I remember reading is exactly what I could use here: look at the old->new color values and do the same mapping to a different image.
Is this something no longer supported, or from some other tool? I can't find anything like it now.