There has been an idea going around that partial image matching works best with Image Feature Descriptor rather than Image Hash. How is this different from Convolutional Neural Networks? https://www.cambridge.org/core/journals/apsipa-transactions-on-signal-and-information-processing/article/survey-on-compact-features-for-visual-content-analysis/A80C3E52CE3D92443DEF40EA44B82DE7