Section 121 · Chapter 15, How Models Work
How Vision-Language Models Process Images
Vision-language models do not see like people. They encode images into tokens and reason over imperfect visual representations.
What to do
- Test visual grounding first.
- Test spatial relationships explicitly.
- Ask questions where position matters: "Which medication is listed under allergies?" or "Which checkout button is disabled?" Test text reading separately from reasoning.
- Keep OCR truth, bounding boxes, and expected text spans as eval evidence, especially for forms, prescriptions, invoices, contracts, screenshots, labels, and charts.
- Test uncertainty and refusal.
Evidence to preserve
- Include small fonts, handwritten notes, rotated labels, mirrored images, low contrast, cropped documents, multi-column layouts, tables, legends, axes, overlapping objects, shadows, reflections, and screenshots with modals or hidden disabled states.
- Store the image, transformed variants, prompt, model version, OCR output, bounding boxes, expected answer, refusal criteria, tool trace, and reviewer rationale together.
- Preserve the inputs, versions, configurations, raw outcomes, and results for vision-language model, vision language models process images needed to reproduce work on How Vision-Language Models Process Images.
- Report results for vision-language model, vision language models process images by relevant slice, separate blocker failures from averages, state uncertainty and blind spots, and connect the result to a release decision.
Expert note
In a real release review, use image perturbations, OCR ground truth, bounding boxes, chart-data checks, document layout tests, accessibility labels, privacy checks, and adversarial prompt-in-image tests. Treat fluent vision-language answers as claims that still need grounding evidence. Store the image, transformed variants, prompt, model version, OCR output, bounding boxes, expected answer, refusal criteria, tool trace, and reviewer rationale together.
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Cite this page
Jason Arbon. "How Vision-Language Models Process Images." Testing AI Knowledge Edition, section 121.
https://jarbon.ai/testing-ai/knowledge/ch121-vision-language-models-process-images.html