diff --git a/FirebaseVertexAI/Tests/Unit/Types/Imagen/ImageGenerationParametersTests.swift b/FirebaseVertexAI/Tests/Unit/Types/Imagen/ImageGenerationParametersTests.swift
index f96be35919a..f50f1646c8d 100644
--- a/FirebaseVertexAI/Tests/Unit/Types/Imagen/ImageGenerationParametersTests.swift
+++ b/FirebaseVertexAI/Tests/Unit/Types/Imagen/ImageGenerationParametersTests.swift
@@ -24,6 +24,175 @@ final class ImageGenerationParametersTests: XCTestCase {
     encoder.outputFormatting = [.sortedKeys, .prettyPrinted, .withoutEscapingSlashes]
   }
 
+  func testDefaultParameters_noneSpecified() throws {
+    let expectedParameters = ImageGenerationParameters(
+      sampleCount: 1,
+      storageURI: nil,
+      negativePrompt: nil,
+      aspectRatio: nil,
+      safetyFilterLevel: nil,
+      personGeneration: nil,
+      outputOptions: nil,
+      addWatermark: nil,
+      includeResponsibleAIFilterReason: true
+    )
+
+    let parameters = ImagenModel.imageGenerationParameters(
+      storageURI: nil,
+      generationConfig: nil,
+      safetySettings: nil
+    )
+
+    XCTAssertEqual(parameters, expectedParameters)
+  }
+
+  func testDefaultParameters_includeStorageURI() throws {
+    let storageURI = "gs://test-bucket/path"
+    let expectedParameters = ImageGenerationParameters(
+      sampleCount: 1,
+      storageURI: storageURI,
+      negativePrompt: nil,
+      aspectRatio: nil,
+      safetyFilterLevel: nil,
+      personGeneration: nil,
+      outputOptions: nil,
+      addWatermark: nil,
+      includeResponsibleAIFilterReason: true
+    )
+
+    let parameters = ImagenModel.imageGenerationParameters(
+      storageURI: storageURI,
+      generationConfig: nil,
+      safetySettings: nil
+    )
+
+    XCTAssertEqual(parameters, expectedParameters)
+  }
+
+  func testParameters_includeGenerationConfig() throws {
+    let sampleCount = 2
+    let negativePrompt = "test-negative-prompt"
+    let aspectRatio = ImagenAspectRatio.landscape16x9
+    let compressionQuality = 80
+    let imageFormat = ImagenImageFormat.jpeg(compressionQuality: compressionQuality)
+    let addWatermark = true
+    let generationConfig = ImagenGenerationConfig(
+      numberOfImages: sampleCount,
+      negativePrompt: negativePrompt,
+      aspectRatio: aspectRatio,
+      imageFormat: imageFormat,
+      addWatermark: addWatermark
+    )
+    let expectedParameters = ImageGenerationParameters(
+      sampleCount: sampleCount,
+      storageURI: nil,
+      negativePrompt: negativePrompt,
+      aspectRatio: aspectRatio.rawValue,
+      safetyFilterLevel: nil,
+      personGeneration: nil,
+      outputOptions: ImageGenerationOutputOptions(
+        mimeType: imageFormat.mimeType,
+        compressionQuality: imageFormat.compressionQuality
+      ),
+      addWatermark: addWatermark,
+      includeResponsibleAIFilterReason: true
+    )
+
+    let parameters = ImagenModel.imageGenerationParameters(
+      storageURI: nil,
+      generationConfig: generationConfig,
+      safetySettings: nil
+    )
+
+    XCTAssertEqual(parameters, expectedParameters)
+    XCTAssertEqual(parameters.aspectRatio, "16:9")
+    XCTAssertEqual(parameters.outputOptions?.mimeType, "image/jpeg")
+    XCTAssertEqual(parameters.outputOptions?.compressionQuality, compressionQuality)
+  }
+
+  func testDefaultParameters_includeSafetySettings() throws {
+    let safetyFilterLevel = ImagenSafetySettings.SafetyFilterLevel.blockOnlyHigh
+    let personGeneration = ImagenSafetySettings.PersonGeneration.allowAll
+    let includeFilterReason = false
+    let safetySettings = ImagenSafetySettings(
+      safetyFilterLevel: safetyFilterLevel,
+      includeFilterReason: includeFilterReason,
+      personGeneration: personGeneration
+    )
+    let expectedParameters = ImageGenerationParameters(
+      sampleCount: 1,
+      storageURI: nil,
+      negativePrompt: nil,
+      aspectRatio: nil,
+      safetyFilterLevel: safetyFilterLevel.rawValue,
+      personGeneration: personGeneration.rawValue,
+      outputOptions: nil,
+      addWatermark: nil,
+      includeResponsibleAIFilterReason: includeFilterReason
+    )
+
+    let parameters = ImagenModel.imageGenerationParameters(
+      storageURI: nil,
+      generationConfig: nil,
+      safetySettings: safetySettings
+    )
+
+    XCTAssertEqual(parameters, expectedParameters)
+    XCTAssertEqual(parameters.safetyFilterLevel, "block_only_high")
+    XCTAssertEqual(parameters.personGeneration, "allow_all")
+  }
+
+  func testParameters_includeAll() throws {
+    let storageURI = "gs://test-bucket/path"
+    let sampleCount = 4
+    let negativePrompt = "test-negative-prompt"
+    let aspectRatio = ImagenAspectRatio.portrait3x4
+    let imageFormat = ImagenImageFormat.png()
+    let addWatermark = false
+    let generationConfig = ImagenGenerationConfig(
+      numberOfImages: sampleCount,
+      negativePrompt: negativePrompt,
+      aspectRatio: aspectRatio,
+      imageFormat: imageFormat,
+      addWatermark: addWatermark
+    )
+    let safetyFilterLevel = ImagenSafetySettings.SafetyFilterLevel.blockNone
+    let personGeneration = ImagenSafetySettings.PersonGeneration.blockAll
+    let includeFilterReason = false
+    let safetySettings = ImagenSafetySettings(
+      safetyFilterLevel: safetyFilterLevel,
+      includeFilterReason: includeFilterReason,
+      personGeneration: personGeneration
+    )
+    let expectedParameters = ImageGenerationParameters(
+      sampleCount: sampleCount,
+      storageURI: storageURI,
+      negativePrompt: negativePrompt,
+      aspectRatio: aspectRatio.rawValue,
+      safetyFilterLevel: safetyFilterLevel.rawValue,
+      personGeneration: personGeneration.rawValue,
+      outputOptions: ImageGenerationOutputOptions(
+        mimeType: imageFormat.mimeType,
+        compressionQuality: imageFormat.compressionQuality
+      ),
+      addWatermark: addWatermark,
+      includeResponsibleAIFilterReason: includeFilterReason
+    )
+
+    let parameters = ImagenModel.imageGenerationParameters(
+      storageURI: storageURI,
+      generationConfig: generationConfig,
+      safetySettings: safetySettings
+    )
+
+    XCTAssertEqual(parameters, expectedParameters)
+    XCTAssertEqual(parameters.aspectRatio, "3:4")
+    XCTAssertEqual(parameters.safetyFilterLevel, "block_none")
+    XCTAssertEqual(parameters.personGeneration, "dont_allow")
+    XCTAssertEqual(parameters.outputOptions?.mimeType, "image/png")
+    XCTAssertNil(parameters.outputOptions?.compressionQuality)
+  }
+
   // MARK: - Encoding Tests
 
   func testEncodeParameters_allSpecified() throws {