[BUG] Base64-encoded string throws exception while invoking image analysis

[justinyoo]

Describe the bug

• Docs link: https://platform.openai.com/docs/guides/images-vision?api-mode=responses&format=base64-encoded
• While running the code sample, https://github.com/justinyoo/openai-dotnet/blob/docs/images-vision/docs/guides/images-vision/responses/analyze_images_passing_base64_string.cs, it's OK to use either stream or byte array. But base64-encoded string throws an exception like:

Unhandled exception. System.ClientModel.ClientResultException: HTTP 400 (invalid_request_error: invalid_value)
Parameter: input

The image data you provided does not represent a valid image. Please check your input and try again with one of the supported image formats: ['image/jpeg', 'image/png', 'image/gif', 'image/webp'].

Steps to reproduce

1. Run this code, https://github.com/justinyoo/openai-dotnet/blob/docs/images-vision/docs/guides/images-vision/responses/analyze_images_passing_base64_string.cs
2. See the error below:

Unhandled exception. System.ClientModel.ClientResultException: HTTP 400 (invalid_request_error: invalid_value)
Parameter: input

The image data you provided does not represent a valid image. Please check your input and try again with one of the supported image formats: ['image/jpeg', 'image/png', 'image/gif', 'image/webp'].
   at OpenAI.ClientPipelineExtensions.ProcessMessage(ClientPipeline pipeline, PipelineMessage message, RequestOptions options)
   at OpenAI.Responses.OpenAIResponseClient.CreateResponse(BinaryContent content, RequestOptions options)
   at OpenAI.Responses.OpenAIResponseClient.CreateResponse(IEnumerable`1 inputItems, ResponseCreationOptions options, CancellationToken cancellationToken)
   at Program.<Main>$(String[] args) in C:\Users\justi\dev\gh\openai-dotnet\docs\guides\images-vision\responses\analyze_images_passing_base64_string.cs:line 43
   at Program.<Main>(String[] args)

Code snippets

Here's the code snippet link: https://github.com/justinyoo/openai-dotnet/blob/docs/images-vision/docs/guides/images-vision/responses/analyze_images_passing_base64_string.cs

OS

Windows

.NET version

.NET 10 RC1

Library version

2.4.0

[joseharriaga]

Thank you for reaching out, @justinyoo ! In the .NET library, you don't need to convert the data to a base64-encoded string yourself because we handle that on your behalf. You just need to pass the raw image data as BinaryData (which is what you're doing in your example when you create the BinaryData directly from a stream or from a byte array). I suspect that the error you're seeing comes from you encoding the image data and then us encoding that a second time.

[justinyoo]

I suspect that the error you're seeing comes from you encoding the image data and then us encoding that a second time.

Thanks @joseharriaga for the comment! So, we can use both stream and byte array but not base64-encoded string. I'll only include both cases in the example.