  The recent Segment Anything Model (SAM) represents a big leap in scaling up
segmentation models, allowing for powerful zero-shot capabilities and flexible
prompting. Despite being trained with 1.1 billion masks, SAM's mask prediction
quality falls short in many cases, particularly when dealing with objects that
have intricate structures. We propose HQ-SAM, equipping SAM with the ability to
accurately segment any object, while maintaining SAM's original promptable
design, efficiency, and zero-shot generalizability. Our careful design reuses
and preserves the pre-trained model weights of SAM, while only introducing
minimal additional parameters and computation. We design a learnable
High-Quality Output Token, which is injected into SAM's mask decoder and is
responsible for predicting the high-quality mask. Instead of only applying it
on mask-decoder features, we first fuse them with early and final ViT features
for improved mask details. To train our introduced learnable parameters, we
compose a dataset of 44K fine-grained masks from several sources. HQ-SAM is
only trained on the introduced detaset of 44k masks, which takes only 4 hours
on 8 GPUs. We show the efficacy of HQ-SAM in a suite of 10 diverse segmentation
datasets across different downstream tasks, where 8 out of them are evaluated
in a zero-shot transfer protocol. Our code and pretrained models are at
https://github.com/SysCV/SAM-HQ.
