I remember reading up on the process used in that opening scene and it’s quite complex. Of course the results are extremely impressive, with the work being worth it. But to carry an entire film with a CG-hybrid de-aged actor would be very difficult, at least if you don’t want limitations.

For example, the shot I show above was obviously done in photoshop, but you could very easily carry that over into after effects with the new advanced face tracker. Problem is some expressions of Harrison are so drastically different from his younger years, that they seem near impossible to process. The shot above he has pretty contained expressions, but when he emotes to a high degree the work becomes very difficult to avoid the uncanny valley effect.

Of course, you can help this by sacrificing some age by blending the original and an over-processed “young version”. You can also use an additional layer to between the two to further deemphasize certain facial features that are more important to remove/smooth, which I also used.

The Luke shot on the other hand was simply the airbrushing over the original.