2014Exemplar CNNDiscriminative Unsupervised Feature Learning with Exemplar CNNs
Pretext
Take one patch, distort it a dozen ways, and declare every distortion a member of the same class. Trivial as it sounds, it planted the seed the whole field would grow from: different views of one image should mean the same thing.
First principles deep-dive →
2015Context PredictionUnsupervised Visual Representation Learning by Context Prediction
Pretext
Show two patches; ask where the second sits relative to the first — above, to the left, diagonally down. To place a wheel beneath a car window, the model must grasp object parts and spatial layout.
2016Colorful Image ColorizationColorful Image Colorization
Pretext
Hand the model a greyscale photo; ask for the colour back. Skies lean blue, grass green, skin warm — getting it right quietly demands semantics, which makes colourisation a surprisingly strong teacher.
2018RotNetUnsupervised Representation Learning by Predicting Image Rotations
Pretext
Rotate by 0°, 90°, 180° or 270° and classify the angle — four classes, free labels. To know a cat is upside down you must first know what an upright cat looks like.