I love it when movies have good title and credit sequences, and in some movies they turn out to be better than the movie itself. When I saw the first Sherlock Holmes movie I thought they did a really good job on the credit sequence. Here is that sequence in case you need a refresher:
This was years ago now, but I thought the ink effect in the sequence was great so I decided to figure out how they did it. Here is what you need to do:
The whole effect is pretty much done with ink drop footage and luma mattes in After Effects. The logic behind the effect is to use ink drops to transition from video footage to a still image (drawing) and back again. Sounds easy enough, but the trick is in how you use the ink drops to reveal the drawing.
Basically what you need to do is take some footage of ink drops and put that footage on a layer above whatever it is you want to reveal (like a sketch in the sherlock holmes sequence). On the sketch layer you change its trackmat to “Luma inverted” so that the sketch is revealed as the ink drops fall/spread (but make sure the ink layer’s visibility is off). You may have to color correct the ink footage to get it black and the background white (or the other way around if you’re using Luma rather than Luma inverted).
Here is a link to some free ink drop footage to get you started: