[BUG]: Image not shown (Langchain / Google VertexAI)

[dardT]

Where do you use Phoenix

Self-hosted

What version of Phoenix are you using?

11.29.0

What happened?

I use Arize-Phoenix to trace my langchain/langgraph application, and it appears that the images are not displayed even though they seem to be captured by OpenTelemetry.

I wonder why, do you have any ideas ?

In the following screenshot there's supposedly 2 images but it does the same with only one.

What's worth to be mentioned is that they are logged within Langchain 1.0+ HumanMessage in the following way :

text_message = {"type": "text", "content": "Hello, world"}
image_message = {
                    "type": "image_url",
                    "image_url": {"url": f"data:image/jpeg;base64,{image_base64}"},
                }

message = HumanMessage(content=[text_message, image_message, image_message])


agent = create_agent(...)

agent.invoke({"messages": [message]})

Additional information

• Phoenix is self-hosted in a local K8S cluster, using Helm + Skaffold

Notable dependencies :

• openinference-instrumentation-langchain>=0.1.50
• arize-phoenix-otel>=0.13.0
• langchain>=1.0
• langgraph>=1.0
• langchain-google-vertexai>=2.0.24

[dosubot]

Hi @dardT! I'm Dosu and I’m helping the phoenix team.

This is a known issue: Phoenix may mask or drop base64-encoded images if they exceed a default size limit, which causes them not to display in the UI—even though they're captured by OpenTelemetry. To fix this, set the environment variable OPENINFERENCE_BASE64_IMAGE_MAX_LENGTH to a large value (for example, 1000000 or higher) at the very start of your application, before any Phoenix/OpenInference imports. Also, set OPENINFERENCE_HIDE_INPUTS and OPENINFERENCE_HIDE_INPUT_IMAGES to "False" to ensure images aren't hidden. In Kubernetes, make sure these are set as container environment variables and restart your pods after updating them. This should resolve the missing image issue in Phoenix UI for traced Langchain HumanMessages with images reference reference.

If images still don't show, check for errors in Phoenix and browser logs, and verify your instrumentation libraries are up to date and correctly propagating image payloads.

To reply, just mention @dosu.

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[dardT]

Fixed with setting OPENINFERENCE_BASE64_IMAGE_MAX_LENGTH to a higher value. Kudos bot