Privacy-preserving text to image matching

A method for text-to-image matching includes generating representations of text images, such as license plate images, by embedding each text image into a first vectorial space with a first embedding function. With a second embedding function, a character string, such as a license plate number to be matched, is embedded into a second vectorial space to generate a character string representation. A compatibility is computed between the character string representation and one or more of the text image representations to identify a matching one. The compatibility is computed with a function that uses a transformation which is learned on a training set of labeled images. The learning uses a loss function that aggregates a text-to-image-loss and an image-to-text loss over the training set. The image-to-text loss penalizes the transformation when it correctly ranks a pair of character string representations, given an image representation corresponding to one of them.