  Curation methods for massive vision-language datasets trade off between
dataset size and quality. However, even the highest quality of available
curated captions are far too short to capture the rich visual detail in an
image. To show the value of dense and highly-aligned image-text pairs, we
collect the Densely Captioned Images (DCI) dataset, containing 7805 natural
images human-annotated with mask-aligned descriptions averaging above 1000
words each. With precise and reliable captions associated with specific parts
of an image, we can evaluate vision-language models' (VLMs) understanding of
image content with a novel task that matches each caption with its
corresponding subcrop. As current models are often limited to 77 text tokens,
we also introduce a summarized version (sDCI) in which each caption length is
limited. We show that modern techniques that make progress on standard
benchmarks do not correspond with significant improvement on our sDCI based
benchmark. Lastly, we finetune CLIP using sDCI and show significant
improvements over the baseline despite a small training set. By releasing the
first human annotated dense image captioning dataset, we hope to enable the
development of new benchmarks or fine-tuning recipes for the next generation of
VLMs to come.
