You can change the sample_size parameter to control many image-caption pairs will be used for training the dual encoder model. In this example we set train_size to 30,000 images, which is about 35% of the dataset. We use 2 captions for each image, thus producing 60,000 image-caption pairs. The size of the training set affects the quality of the produced encoders, but more examples would lead to longer training time.