A system and method for constructing a training dataset and training a neural network include obtaining a searchable portable document format (PDF) document, identifying a bounding box defining a region in a background image that is associated with an overlaying text object defined in the PDF document, determining an image crop of the PDF document according to the bounding box, and generating a training data sample for the training dataset, the training data sample comprising a data pair of the image crop and the associated text object.