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    media

    Image
    Caption
    Converter

    Generate natural-language captions for images using a vision-language model. Produces concise, descriptive sentences suitable for alt text, content indexing, and accessibility compliance.

    Max file size: 50 MB
    Estimated: 1-4 sec per image
    6 input formats

    How It Works

    1

    Upload an image or provide a URL.

    2

    A vision-language model analyzes the image content.

    3

    A caption is generated describing the main subjects and actions.

    4

    The caption is returned along with a confidence score.

    5

    Multiple caption variants can be requested for A/B testing.

    Code Examples

    import os, requests
    
    API = "https://api.mixpeek.com"
    H = {"Authorization": f"Bearer {os.environ['MIXPEEK_API_KEY']}",
         "X-Namespace": os.environ["NAMESPACE_ID"]}
    
    # 1. a bucket, with a schema that declares the field you will send
    bucket = requests.post(f"{API}/v1/buckets", headers=H, json={
        "bucket_name": "image-inputs",
        "bucket_schema": {"properties": {"image": {"type": "image"}}},
    }).json()
    
    # 2. land the file as an object. the URL goes in data, on the blob
    requests.post(f"{API}/v1/buckets/{bucket['bucket_id']}/objects", headers=H, json={
        "key_prefix": "run-1",
        "blobs": [{"property": "image", "type": "image",
                   "data": "https://example.com/photo.jpg"}],
    })
    
    # 3. a collection over that bucket, running the extractor
    collection = requests.post(f"{API}/v1/collections", headers=H, json={
        "collection_name": "image-to-caption",
        "source": {"type": "bucket", "bucket_ids": [bucket["bucket_id"]]},
        "feature_extractor": {"feature_extractor_name": "image_extractor", "version": "v1"},
    }).json()
    
    # 4. run extraction over the bucket
    requests.post(f"{API}/v1/buckets/{bucket['bucket_id']}/batches", headers=H, json={
        "collection_ids": [collection["collection_id"]],
        "auto_submit": True,
    })
    
    # 5. read the output
    docs = requests.get(
        f"{API}/v1/collections/{collection['collection_id']}/documents", headers=H
    ).json()
    print(docs)

    Use Cases

    Auto-generate alt text for web accessibility (WCAG compliance)
    Create captions for social media image posts
    Index product images with descriptive metadata
    Enrich image search with natural language descriptions

    Supported Input Formats

    JPEG
    PNG
    WebP
    TIFF
    BMP
    GIF

    Quick Info

    Categorymedia
    Max File Size50 MB
    Est. Time1-4 sec per image

    Processing millions of files?

    Run this as a managed pipeline over your whole library, no infrastructure to build or maintain. Talk to us about processing at scale.

    Run it over a library

    Mixpeek runs this conversion as a pipeline over a whole library in your object storage, with the output landing as queryable documents. It is not a single-file converter.

    Frequently Asked Questions

    Ready to convert image to caption?

    Start using the Mixpeek Image to Caption in minutes. Sign up for a free API key and follow the documentation to get started.