  Diffusion models have revolutionized generative content creation and
text-to-image (T2I) diffusion models in particular have increased the creative
freedom of users by allowing scene synthesis using natural language. T2I models
excel at synthesizing concepts such as nouns, appearances, and styles. To
enable customized content creation based on a few example images of a concept,
methods such as Textual Inversion and DreamBooth invert the desired concept and
enable synthesizing it in new scenes. However, inverting more general concepts
that go beyond object appearance and style (adjectives and verbs) through
natural language, remains a challenge. Two key characteristics of these
concepts contribute to the limitations of current inversion methods. 1)
Adjectives and verbs are entangled with nouns (subject) and can hinder
appearance-based inversion methods, where the subject appearance leaks into the
concept embedding and 2) describing such concepts often extends beyond single
word embeddings (being frozen in ice, walking on a tightrope, etc.) that
current methods do not handle.
  In this study, we introduce Lego, a textual inversion method designed to
invert subject entangled concepts from a few example images. Lego disentangles
concepts from their associated subjects using a simple yet effective Subject
Separation step and employs a Context Loss that guides the inversion of
single/multi-embedding concepts. In a thorough user study, Lego-generated
concepts were preferred over 70% of the time when compared to the baseline.
Additionally, visual question answering using a large language model suggested
Lego-generated concepts are better aligned with the text description of the
concept.
