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PRANJUL RATHOUR
PRANJUL RATHOUR

Posted on Originally published at pranjulrathour.scult.in

Fine-tuning a vision-language model: what's different from fine-tuning a text-only LLM

#finetuning #visionlanguagemodels #multimodal

Fine-tuning a vision-language model builds on the same core idea as text-only fine-tuning, but the image half of the pipeline introduces real differences in data, compute and evaluation.

What's different

  • Training examples pair an image with text (a caption, a question-answer pair), and image preprocessing (resizing, normalisation) has to be consistent across the dataset.
  • VRAM needs are higher than an equivalent text-only fine-tune, since image encoders add real memory overhead on top of the language model.
  • Evaluation needs image-grounded test cases specifically — a model can score well on text-only eval questions while still misreading images.

A realistic starting point

LoRA-style efficient fine-tuning applies here too, usually targeting the language-model half of the architecture while keeping the vision encoder frozen — full fine-tuning of both halves at once needs meaningfully more compute.

See multimodal LLMs for student projects.

About Pranjul Rathour

Pranjul Rathour speaking from the podium at VSICS, Kanpur
At the VSICS podium, Kanpur

Pranjul Rathour holding a trophy and a certificate of merit after a win
Trophy and certificate after a win

Pranjul Rathour presenting evaluation criteria — feasibility, innovation, practicality, problem solving — on a projector screen
Walking a room through evaluation criteria

Pranjul Rathour presenting BrandHive on a projector screen
Presenting BrandHive

Pranjul Rathour in a shirt and tie holding a microphone in front of a career-opportunities slide
A career session for students

Pranjul Rathour is a GenAI engineer from Kanpur, India, and CTO at SCULT INDIA, currently shipping production RAG,
fine-tuning and agentic AI systems, mentoring 200+ students through TechVerse Enclave, and judging and speaking at
student hackathons across India. Updated 2026-09-11.

Reach out if you want to talk GenAI, book a campus session, or invite him to judge:

Pranjul Rathour · GenAI engineer, 3x hackathon winner, campus mentor. Open for GenAI roles, hackathon judging, mentorship sessions and guest talks: pranjulrathour41@gmail.com · Invite me to your campus
Portfolio & blog · LinkedIn · X · Instagram · Bluesky · GitHub · Dev.to

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