Generalizing Visual Language Models: Multiple Architectural Approaches
Source: Lilian Weng09/06/2022, 19:10
Vision-language tasks, such as image captioning and visual question-answering, have evolved beyond traditional object-detection pipelines. Recent research has focused on extending pre-trained language models to process visual signals, resulting in several distinct architectural families.
The first major approach treats image regions as tokens within the sequence processing pipeline. VisualBERT fuses images and text through BERT's self-attention mechanism, discovering cross-modal alignment. SimVLM employs a prefix language model where visual tokens are processed bidirectionally before text generation occurs. CM3 scales this further, training on massive web data to generate richly structured, multimodal outputs including hyperlinks and images.
A complementary strategy maintains frozen language models and adapts only the visual encoding pathway. Frozen and ClipCap exemplify this efficiency-focused approach, translating visual embeddings into the language model's semantic space with minimal parameter training. ClipCap specifically leverages CLIP image embeddings and demonstrates competitive performance despite training only a lightweight mapping network.
Cross-attention mechanisms offer another path for balancing visual and linguistic information. VisualGPT introduces gated activation units to control the mixture of visual and linguistic features; VC-GPT adds cross-attention layers between visual transformers and language decoders. More recent models like MERLOT incorporate temporal reasoning by learning from video, while Flamingo represents an advanced synthesis, accepting interleaved image-text sequences and using Perceiver-based compression for efficient multimodal fusion.