The paper is not super-well written, it kind of hides the underlying idea (which is pretty simple) and doesn't show it clearly on page 1. What ever happened to

The paper is not super-well written, it kind of hides the underlying idea (which is pretty simple) and doesn't show it clearly on page 1. What ever happened to the good old article-writing rules that you need to present a summary of your idea clearly in Figure 1 already? :) My take is that the they guess at an alpha-mask first, then iterate by generating a composite image of the input image (to be segmented) with a uniform background using the proposed alpha, then update the mask using gradient descent on the score of the composite image related to the text-conditioning. They add some extra scoring functions to try to suppress "bad" alpha masks.