Segment Anything 2.1 (SAM 2.1), image

• Original code: https://github.com/facebookresearch/sam2 at 2b90b9f
• Code licence: Apache-2.0 (permissive); files: LICENSE
• Weights licence: Apache-2.0
• Licence evidence: https://github.com/facebookresearch/sam2/blob/main/README.md (License section: model checkpoints and code under Apache 2.0)
• Training data: SA-1B and the SA-V video dataset (plus internal data) per the paper; SA-V itself is under CC BY 4.0, SA-1B under its research licence
• Kernel libraries: dpt_fused
• Variants: sam2.1-hiera-tiny, sam2.1-hiera-small, sam2.1-hiera-base-plus, sam2.1-hiera-large
• Outputs: pred_masks, iou_scores
• Input size: any H x W >= 1, resized inside to the fixed encoder input 1024x1024 (the default export size)
• Tested up to (portable, fp16, RTX 5060 Ti 16 GB): sam2.1-hiera-tiny 1080x1920 (0.3 GiB peak allocated, 0.4 reserved); sam2.1-hiera-small 1080x1920 (0.3 GiB peak allocated, 0.4 reserved); sam2.1-hiera-base-plus 1080x1920 (0.4 GiB peak allocated, 0.6 reserved); sam2.1-hiera-large 1080x1920 (0.7 GiB peak allocated, 0.9 reserved)
• sam2.1-hiera-tiny 1024x1024, first call: portable + torch.compile 13 s (cold Inductor cache), TensorRT fp16 34 s (ONNX + engine).
• sam2.1-hiera-tiny original 1024x1024: torch.autocast(float16) around the call
• sam2.1-hiera-small original 1024x1024: torch.autocast(float16) around the call
• sam2.1-hiera-base-plus original 1024x1024: torch.autocast(float16) around the call
• sam2.1-hiera-large original 1024x1024: torch.autocast(float16) around the call
• sam2.1-hiera-tiny load / first call: original 0.41 s / 0.147 s, portable 0.25 s / 0.017† s, kernels 0.11† s / 0.014† s
• sam2.1-hiera-small load / first call: original 0.48 s / 0.136 s, portable 0.36 s / 0.019† s, kernels 0.13† s / 0.016† s
• sam2.1-hiera-base-plus load / first call: original 0.74 s / 0.143 s, portable 0.43 s / 0.032† s, kernels 0.19† s / 0.025† s
• sam2.1-hiera-large load / first call: original 1.95 s / 0.184 s, portable 1.1 s / 0.068† s, kernels 0.39† s / 0.049† s
• † measured in the speed sweep after the portable load (or an earlier size) in the same process: file cache and kernels are warm, so the time is lower than a fresh start.
• Protocol, median of 5 after 3 warm-up, uint8 CUDA input (synthetic for bench_inputs sizes), card defaults; gc before each load; peak = max over the first call and the timed calls

Measured

One point per ground-truth instance (the interior point farthest from the border); IoU of the best-scored of 3 masks / of the single mask. Original = the original code named under Details, same checkpoint and protocol.

Measured on NVIDIA GeForce RTX 5060 Ti, torch 2.14.1+cu130, fastforks 939adfe8, 2026-11-06.

Parity

CPU, float32: max |diff| <= 0.002 vs the original. GPU, float16 (the default), portable and kernels: mean |diff| <= 3 % and p99 <= 15 % of the reference's median |value| (absolute error of the output pred_masks).