  Despite significant progress in generative AI, comprehensive evaluation
remains challenging because of the lack of effective metrics and standardized
benchmarks. For instance, the widely-used CLIPScore measures the alignment
between a (generated) image and text prompt, but it fails to produce reliable
scores for complex prompts involving compositions of objects, attributes, and
relations. One reason is that text encoders of CLIP can notoriously act as a
"bag of words", conflating prompts such as "the horse is eating the grass" with
"the grass is eating the horse". To address this, we introduce the VQAScore,
which uses a visual-question-answering (VQA) model to produce an alignment
score by computing the probability of a "Yes" answer to a simple "Does this
figure show '{text}'?" question. Though simpler than prior art, VQAScore
computed with off-the-shelf models produces state-of-the-art results across
many (8) image-text alignment benchmarks. We also compute VQAScore with an
in-house model that follows best practices in the literature. For example, we
use a bidirectional image-question encoder that allows image embeddings to
depend on the question being asked (and vice versa). Our in-house model,
CLIP-FlanT5, outperforms even the strongest baselines that make use of the
proprietary GPT-4V. Interestingly, although we train with only images, VQAScore
can also align text with video and 3D models. VQAScore allows researchers to
benchmark text-to-visual generation using complex texts that capture the
compositional structure of real-world prompts. We introduce GenAI-Bench, a more
challenging benchmark with 1,600 compositional text prompts that require
parsing scenes, objects, attributes, relationships, and high-order reasoning
like comparison and logic. GenAI-Bench also offers over 15,000 human ratings
for leading image and video generation models such as Stable Diffusion, DALL-E
3, and Gen2.
