> ## Documentation Index
> Fetch the complete documentation index at: https://docs.qwedai.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Image engine

> QWED's Image Engine verifies image claims using deterministic metadata extraction first, with advisory-only VLM fallback for semantic claims.

The Image Engine verifies claims about images using **deterministic methods first**, with VLM fallback only for complex semantic claims.

## Features

* **Metadata extraction** — dimensions and format (PNG, JPEG, GIF, WebP)
* **Size verification** — exact dimension comparison from metadata
* **Claim classification** — routes claims to the appropriate verifier
* **Advisory VLM cross-check** — optional model fallback for semantic claims

## Usage

```python theme={null}
from qwed_sdk import QWEDClient

client = QWEDClient(api_key="qwed_...")

# Verify claim
result = client.verify_image(
    image_path="chart.png",
    claim="The image is 800x600 pixels"
)

print(result.status)      # "VERIFIED" (deterministic metadata proof)
print(result.is_verified) # True
print(result.result["developer_fields"]["analysis"]["metadata"])  # {"width": 800, "height": 600, "format": "png"}
```

## Claim types

| Claim Type      | Method           | Deterministic? |
| --------------- | ---------------- | -------------- |
| Size/Dimensions | Metadata parsing | ✅ 100%         |
| Format          | Header detection | ✅ 100%         |
| Color           | Pixel sampling   | ⚠️ Partial     |
| Text            | OCR required     | ❌ VLM          |
| Semantic        | Understanding    | ❌ VLM          |

## Result contract

The Image Engine returns a [`DiagnosticResult`](/advanced/diagnostics) whose status depends on which path handled the claim:

| Path                                      | `DiagnosticResult.status` | Notes                                                                                              |
| ----------------------------------------- | ------------------------- | -------------------------------------------------------------------------------------------------- |
| Deterministic evidence supports the claim | `VERIFIED`                | Emits a `proof_ref` bound to pixel or metadata evidence.                                           |
| Deterministic evidence refutes the claim  | `BLOCKED`                 | Fail-closed refutation.                                                                            |
| VLM cross-check only                      | `UNVERIFIABLE`            | VLM results are recorded in `advisory_checks`; the engine never emits `VERIFIED` from a VLM alone. |

This mirrors the [3-tier engine classification](/engines/overview): a VLM signal is advisory and cannot promote a claim to `VERIFIED`.

## VLM cross-check (advisory)

Semantic claims (color, text, visual understanding) cannot be proven deterministically. The core `ImageVerifier` supports a VLM fallback for these claims when instantiated with `use_vlm_fallback=True`; the VLM output is recorded in `advisory_checks` and does not change the diagnostic status. The public `/verify/image` endpoint runs with `use_vlm_fallback=False`, so via the SDK a semantic claim resolves to `UNVERIFIABLE` with the VLM path listed as advisory-only:

```python theme={null}
result = client.verify_image(
    image_path="photo.png",
    claim="The person is smiling"
)

print(result.status)      # "UNVERIFIABLE" (deterministic path cannot verify)
print(result.result["developer_fields"].get("advisory_checks", []))  # [] for SDK/API path
```

## Supported providers for image verification

The Image Engine supports multimodal verification through any provider that accepts image inputs. When you set `ACTIVE_PROVIDER=gemini`, QWED uses Google Gemini's native multimodal capabilities for semantic image claims. Supported image formats are JPEG, PNG, and WebP.

```bash theme={null}
export ACTIVE_PROVIDER=gemini
export GOOGLE_API_KEY=your-google-api-key
```

See [LLM configuration](/getting-started/llm-configuration#google-gemini) for full setup instructions.