1. In a digital media environment to facilitate management of image collections using at least one computing device, a method to automatically generate image captions using weak supervision data comprising: obtaining, by the at least one computing device, a target image for caption analysis; applying, by the at least one computing device, feature extraction to the target image to generate global concepts corresponding to the image; comparing, by the at least one computing device, the target image to images from a source of weakly annotated images to identify visually similar images; building, by the at least one computing device, a collection of keywords for the target image indicative of image details by extracting the keywords from the visually similar images; and supplying, by the at least one computing device, the collection of keywords indicative of image details as the weak supervision data for caption generation along with the global concepts.