Regaind's computer vision API is said to have the ability to analyze the content of photos, so it'll know to surface photos of dogs if you search for "dog", for example. Apple's Photos app has had this feature for a couple of years already, but the acquisition of Regaind could be key to boosting this capability even further and keeping up with Google's machine learning-powered Photos app.
As claimed on Regaind's website, the tech can not only figure out the content of your photos, but also their technical and aesthetic values. This is helpful for hiding duplicates, for finding the best shot in a series of burst shot photos, or for grouping images by color and events. It might make it a lot easier to find and create albums too.
What's particularly interesting is that Regaind can also apparently analyze your face for gender, age and emotion, which sounds very similar to what FaceApp does. Apple could use the face analysis tech not just for doing cool selfie filter tricks like Snapchat and Instagram, but perhaps to also power its animoji feature in the upcoming iPhone X.