What is Label Refinement in the Context of Image Segmentation
The correct context of the refinement key word is segmentation.
Label Refinement in the context of image segmentation is a step to increase the resolution and understanding of the segmentation.
It can be done by exterior knowledge (Like labels on features) or other optimization steps to have a better results of the segmentation (Which basically labeling of the image pixels).
For instance, if the segmentation is based on Super Pixels a Refinement Step could be merging of some Super Pixels.
You may have a look at Label Refinement Network for Coarse to Fine Semantic Segmentation. In this paper they use Multi Scale approach for label segmentation. By using coarse level to refine finder level.