Animating a reflection in a static photo is pretty easy and can be done quite fast. You don’t need to be an expert to add some dynamic motion to your picture.
First open After Effects, import the photo you want to edit, right click on the file and click on “New Comp from Selection”.
Select the Pen Tool, click on the photo in the timeline and mask the reflected area. This works best if the reflected area is clearly separated from the rest of the image.
After this is done, you should only be able to see the water reflection.
Since a large part of the image is now missing, drag the same image down to the timeline again and place it under the masked image.
Now it’s time to animate the reflection. Go to “Effects”, “Distort” and choose “Wave Warp” at the very bottom and apply it to the masked layer.
If you hit playback now you can already see a motion effect.
The value of the “Wave Height” should be lowered and the “Wave Width” increased to make it look more realistic.
Depending on the scenery in the image it can also make sense to lower the “Wave Speed” to get a calming look, rather than a disturbing effect.
The “Direction” of the effect can also be adjusted. This can be useful to customize depending on the camera angle in which the photo was taken.
To make a transition between the masked layer and the static background photo, you can open the “Mask” settings and increase the “Feather” to blur the transition between the two images.
Overall a simple and fast but very effective way to generate a water reflection.
If you want an even more realistic and advanced reflection you can add another effect. Apply the “Turbulent Displace” effect listed in the “Distort” menu. You can then keyframe the “Amount” and “Size”. To do that, simply go to the beginning of the timeline and click the “Stop Watch” icon. Then go to the end of the timeline and change the value of the “Amount” or “Size”. When playing back the video it will now change the distortion effect during the duration of the video.