A Vision Transformer treats an image the way a language model treats a sentence: it splits the image into fixed-size patches, treats each patch like a token, and runs the same self-attention mechanism used in text transformers over those patch tokens.
What this practically implies
- Input resolution and patch size together determine how many tokens the model processes — larger images or smaller patches mean more compute, directly.
- ViTs generally need more training data than convolutional models to reach the same accuracy from scratch, which is why most practical use starts from a pretrained checkpoint rather than training from zero.
- Fine-tuning a pretrained ViT on a specific task is usually far more practical for a student project than training one from scratch.
The one thing worth internalising
Because patches are treated as a sequence, a ViT has no built-in notion of 'nearby pixels matter more' the way a convolution does — it learns that from data via attention. This is why ViTs need either more data or a good pretrained starting point to work well.
See CLIP vs ViT vs a multimodal LLM.
— Pranjul Rathour, GenAI Engineer from Kanpur, India. Open to GenAI roles, hackathon judging, mentorship sessions and guest talks at any campus: pranjulrathour41@gmail.com.