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Gemini Image Understanding

POST /v1beta/models/{model}:generateContent
As of 2026-04-08, successful Crazyrouter and local :4000 retests show:
  • gemini-2.5-pro can reliably read images through inlineData
  • remote image URLs through fileData.fileUri have shown repeated fetch and upstream-body failures
  • the primary recommended request shape for image understanding is therefore inlineData

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Verified Minimal Request

curl "https://crazyrouter.com/v1beta/models/gemini-2.5-pro:generateContent?key=YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "contents": [
      {
        "role": "user",
        "parts": [
          {
            "inlineData": {
              "mimeType": "image/png",
              "data": "BASE64_PNG_DATA"
            }
          },
          {
            "text": "Describe this image in one short sentence."
          }
        ]
      }
    ]
  }'
Observed production response shape: 
{
  "candidates": [
    {
      "content": {
        "parts": [
          {
            "text": "This image shows a smooth multi-color gradient background."
          }
        ]
      }
    }
  ]
}

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Request Notes

  • Prefer inlineData for image understanding
  • Keep mimeType aligned with the actual file format, such as image/png or image/jpeg
  • Put raw Base64 into data without the data:image/...;base64, prefix
  • If you only have a remote image URL, do not treat it as the current primary Gemini image-understanding path on Crazyrouter
For video understanding, see Gemini Video Understanding. For audio understanding, see Gemini Audio Understanding.