ComfyUI-MaskArbiter
ComfyUI-MaskArbiter
A node for ComfyUI that takes a list of masks and returns a single mask based on your criteria.
For example, it can be used to mask the leftmost subject in an image containing more than one subject of the same class. The workflow below demonstrates the difference between Mask Arbiter (top) and traditional Grounding DINO masking (bottom.)
Installation
Simply drag the image above into ComfyUI and use ComfyUI Manager » Install Missing Custom Nodes.
[!NOTE]
ComfyUI-MaskArbiter is packaged with a modified version of the GroundingDinoSAM2Segment node from ComfyUI-SAM2. Look for “GroundingDinoSAM2SegmentList.” This version of the node outputs a list of masks that you can feed into Mask Arbiter. It also enables support for SAM 2.1 models. You do not need this if you are using SAM 3 instead.
[!NOTE]
A quick follow-up to the previous note: I was hoping to eventually retire GroundingDinoSAM2SegmentList from this repository after proposing improvements to ComfyUI-SAM2. However, the relevant issues were incorrectly marked as stale (#34, #42), so the extra node is still required as of September 2025.
Inputs
mask OR masks: A list of masks to process with Mask Arbiter, such as the outputs of Segment Anything. Supports either datatype for compatibility with different masking nodes.sort_by: The method of sorting your masks. Possible options include leftmost (sort left to right), topmost (sort top to bottom), innermost (prioritize closest to center of your image), largest (sort by pixel area occupied), initial (do not sort), random (sort randomly), and merged (combine all masks and merge into one.)reverse: Reverses the mask list order after sorting. For example, if you sort by leftmost and enable reverse, you’ll get the rightmost subject.index: The individual mask to return after sorting, zero-indexed.Outputs
MASK: A mask of the selected index after sorting.MASKS: The entire mask list after sorting.This script was adapted from the [txt2mask] shortcode of Unprompted, my Automatic1111 extension.