  The paper introduces PaintSeg, a new unsupervised method for segmenting
objects without any training. We propose an adversarial masked contrastive
painting (AMCP) process, which creates a contrast between the original image
and a painted image in which a masked area is painted using off-the-shelf
generative models. During the painting process, inpainting and outpainting are
alternated, with the former masking the foreground and filling in the
background, and the latter masking the background while recovering the missing
part of the foreground object. Inpainting and outpainting, also referred to as
I-step and O-step, allow our method to gradually advance the target
segmentation mask toward the ground truth without supervision or training.
PaintSeg can be configured to work with a variety of prompts, e.g. coarse
masks, boxes, scribbles, and points. Our experimental results demonstrate that
PaintSeg outperforms existing approaches in coarse mask-prompt, box-prompt, and
point-prompt segmentation tasks, providing a training-free solution suitable
for unsupervised segmentation.
