.Net: Added support for OpenAI image detail level property (#9561)

### Motivation and Context

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Resolves: #4759

This PR adds a support for the `detail` property in the OpenAI image
API. The property can be configured using `ImageContent.Metadata`
property.

`ImageContent.Metadata` usage:
```csharp
chatHistory.AddUserMessage(
[
    new TextContent("What’s in this image?"),
    new ImageContent(imageBytes, "image/jpg") { Metadata = new Dictionary<string, object?> { ["ChatImageDetailLevel"] = "high" } }
]);
```

### Contribution Checklist

<!-- Before submitting this PR, please make sure: -->

- [x] The code builds clean without any errors or warnings
- [x] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [x] All unit tests pass, and I have added new tests where possible
- [x] I didn't break anyone 😄

dotnet/samples/Concepts/ChatCompletion/OpenAI_ChatCompletionWithVision.cs

@@ -56,4 +56,28 @@ public async Task LocalImageAsync()
 
         Console.WriteLine(reply.Content);
     }
+
+    [Fact]
+    public async Task LocalImageWithImageDetailInMetadataAsync()
+    {
+        var imageBytes = await EmbeddedResource.ReadAllAsync("sample_image.jpg");
+
+        var kernel = Kernel.CreateBuilder()
+            .AddOpenAIChatCompletion("gpt-4-vision-preview", TestConfiguration.OpenAI.ApiKey)
+            .Build();
+
+        var chatCompletionService = kernel.GetRequiredService<IChatCompletionService>();
+
+        var chatHistory = new ChatHistory("You are a friendly assistant.");
+
+        chatHistory.AddUserMessage(
+        [
+            new TextContent("What’s in this image?"),
+            new ImageContent(imageBytes, "image/jpg") { Metadata = new Dictionary<string, object?> { ["ChatImageDetailLevel"] = "high" } }
+        ]);
+
+        var reply = await chatCompletionService.GetChatMessageContentAsync(chatHistory);
+
+        Console.WriteLine(reply.Content);
+    }
 }

dotnet/src/Connectors/Connectors.OpenAI.UnitTests/Services/OpenAIChatCompletionServiceTests.cs

@@ -642,6 +642,69 @@ public async Task GetChatMessageContentsWithChatMessageContentItemCollectionAndS
         Assert.Equal("image_url", contentItems[1].GetProperty("type").GetString());
     }
 
+    [Theory]
+    [MemberData(nameof(ImageContentMetadataDetailLevelData))]
+    public async Task GetChatMessageContentsHandlesImageDetailLevelInMetadataCorrectlyAsync(object? detailLevel, string? expectedDetailLevel)
+    {
+        // Arrange
+        var chatCompletion = new OpenAIChatCompletionService(modelId: "gpt-4-vision-preview", apiKey: "NOKEY", httpClient: this._httpClient);
+
+        using var response = new HttpResponseMessage(System.Net.HttpStatusCode.OK) { Content = new StringContent(ChatCompletionResponse) };
+        this._messageHandlerStub.ResponseToReturn = response;
+
+        var chatHistory = new ChatHistory();
+        chatHistory.AddUserMessage(
+        [
+            new ImageContent(new Uri("https://image")) { Metadata = new Dictionary<string, object?> { ["ChatImageDetailLevel"] = detailLevel } }
+        ]);
+
+        // Act
+        await chatCompletion.GetChatMessageContentsAsync(chatHistory);
+
+        // Assert
+        var actualRequestContent = Encoding.UTF8.GetString(this._messageHandlerStub.RequestContent!);
+        Assert.NotNull(actualRequestContent);
+        var optionsJson = JsonSerializer.Deserialize<JsonElement>(actualRequestContent);
+
+        var messages = optionsJson.GetProperty("messages");
+
+        Assert.Equal(1, messages.GetArrayLength());
+
+        var contentItems = messages[0].GetProperty("content");
+        Assert.Equal(1, contentItems.GetArrayLength());
+
+        Assert.Equal("image_url", contentItems[0].GetProperty("type").GetString());
+
+        var imageProperty = contentItems[0].GetProperty("image_url");
+
+        Assert.Equal("https://image/", imageProperty.GetProperty("url").GetString());
+
+        if (detailLevel is null || (detailLevel is string detailLevelString && string.IsNullOrWhiteSpace(detailLevelString)))
+        {
+            Assert.False(imageProperty.TryGetProperty("detail", out _));
+        }
+        else
+        {
+            Assert.Equal(expectedDetailLevel, imageProperty.GetProperty("detail").GetString());
+        }
+    }
+
+    [Fact]
+    public async Task GetChatMessageContentsThrowsExceptionWithInvalidImageDetailLevelInMetadataAsync()
+    {
+        // Arrange
+        var chatCompletion = new OpenAIChatCompletionService(modelId: "gpt-4-vision-preview", apiKey: "NOKEY", httpClient: this._httpClient);
+
+        var chatHistory = new ChatHistory();
+        chatHistory.AddUserMessage(
+        [
+            new ImageContent(new Uri("https://image")) { Metadata = new Dictionary<string, object?> { ["ChatImageDetailLevel"] = "invalid_value" } }
+        ]);
+
+        // Act & Assert
+        await Assert.ThrowsAsync<ArgumentException>(() => chatCompletion.GetChatMessageContentsAsync(chatHistory));
+    }
+
     [Fact]
     public async Task FunctionCallsShouldBePropagatedToCallersViaChatMessageItemsOfTypeFunctionCallContentAsync()
     {
@@ -1558,6 +1621,15 @@ public async Task OnAutoFunctionInvocationAsync(AutoFunctionInvocationContext co
         }
         """;
 
+    public static TheoryData<object?, string?> ImageContentMetadataDetailLevelData => new()
+    {
+        { "auto", "auto" },
+        { "high", "high" },
+        { "low", "low" },
+        { "", null },
+        { null, null }
+    };
+
 #pragma warning disable CS8618, CA1812
     private sealed class MathReasoning
     {

dotnet/src/Connectors/Connectors.OpenAI/Core/ClientCore.ChatCompletion.cs

@@ -802,19 +802,44 @@ private static List<ChatMessage> CreateRequestMessages(ChatMessageContent messag
 
     private static ChatMessageContentPart GetImageContentItem(ImageContent imageContent)
     {
+        ChatImageDetailLevel? detailLevel = GetChatImageDetailLevel(imageContent);
+
         if (imageContent.Data is { IsEmpty: false } data)
         {
-            return ChatMessageContentPart.CreateImagePart(BinaryData.FromBytes(data), imageContent.MimeType);
+            return ChatMessageContentPart.CreateImagePart(BinaryData.FromBytes(data), imageContent.MimeType, detailLevel);
         }
 
         if (imageContent.Uri is not null)
         {
-            return ChatMessageContentPart.CreateImagePart(imageContent.Uri);
+            return ChatMessageContentPart.CreateImagePart(imageContent.Uri, detailLevel);
         }
 
         throw new ArgumentException($"{nameof(ImageContent)} must have either Data or a Uri.");
     }
 
+    private static ChatImageDetailLevel? GetChatImageDetailLevel(ImageContent imageContent)
+    {
+        const string DetailLevelProperty = "ChatImageDetailLevel";
+
+        if (imageContent.Metadata is not null &&
+            imageContent.Metadata.TryGetValue(DetailLevelProperty, out object? detailLevel) &&
+            detailLevel is not null)
+        {
+            if (detailLevel is string detailLevelString && !string.IsNullOrWhiteSpace(detailLevelString))
+            {
+                return detailLevelString.ToUpperInvariant() switch
+                {
+                    "AUTO" => ChatImageDetailLevel.Auto,
+                    "LOW" => ChatImageDetailLevel.Low,
+                    "HIGH" => ChatImageDetailLevel.High,
+                    _ => throw new ArgumentException($"Unknown image detail level '{detailLevelString}'. Supported values are 'Auto', 'Low' and 'High'.")
+                };
+            }
+        }
+
+        return null;
+    }
+
     private OpenAIChatMessageContent CreateChatMessageContent(OpenAIChatCompletion completion, string targetModel)
     {
         var message = new OpenAIChatMessageContent(completion, targetModel, this.GetChatCompletionMetadata(completion));

dotnet/src/SemanticKernel.UnitTests/Contents/ImageContentTests.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft. All rights reserved.
 
 using System;
+using System.Collections.Generic;
 using System.Text;
 using System.Text.Json;
 using Microsoft.SemanticKernel;
@@ -241,6 +242,25 @@ public void EmptyConstructorSerializationAndDeserializationAsExpected()
         Assert.Null(deserialized.Metadata);
     }
 
+    [Fact]
+    public void MetadataSerializationAndDeserializationWorksCorrectly()
+    {
+        // Arrange
+        var content = new ImageContent()
+        {
+            Metadata = new Dictionary<string, object?> { ["ChatImageDetailLevel"] = "high" }
+        };
+
+        // Act
+        var serialized = JsonSerializer.Serialize(content);
+        var deserialized = JsonSerializer.Deserialize<ImageContent>(serialized);
+
+        // Assert
+        Assert.NotNull(deserialized?.Metadata);
+        Assert.True(deserialized.Metadata.ContainsKey("ChatImageDetailLevel"));
+        Assert.Equal("high", deserialized.Metadata["ChatImageDetailLevel"]?.ToString());
+    }
+
     [Theory]
     [InlineData("http://localhost:9090/")]
     [InlineData(null)]