gemini-image-chat

Gemini Image Chat Sample

This sample is part of the AI Sample Catalog. To build and run this sample, you should clone the entire repository.

Description

This sample demonstrates a chat bot using Gemini 3 Pro Image (a.k.a Nano Banana Pro) that can understand both text and images and generate images and text in return. Users can send a message that includes an image, and the generative model will respond based on the multimodal input. This showcases how to build powerful, interactive image generation chat experiences with the Gemini API.

How it works

The application uses the Firebase AI SDK (see How to run) for Android to interact with the Gemini 3 Pro Image model. The core logic is in the GeminiImageChatViewModel.kt file. When a user sends a message with an image, a content block is created that includes both the text and the Bitmap of the image. This multimodal content is then sent to the model.

Here is how the model is instantiated:

 Firebase.ai(backend = GenerativeBackend.googleAI()).generativeModel(
            "gemini-3-pro-image-preview",
            generationConfig = generationConfig {
                temperature = 0.9f
                topK = 32
                topP = 1f
                maxOutputTokens = 4096
                responseModalities = listOf(ResponseModality.TEXT, ResponseModality.IMAGE)
            },
            safetySettings = listOf(
                SafetySetting(HarmCategory.HARASSMENT, HarmBlockThreshold.MEDIUM_AND_ABOVE),
                SafetySetting(HarmCategory.HATE_SPEECH, HarmBlockThreshold.MEDIUM_AND_ABOVE),
                SafetySetting(HarmCategory.SEXUALLY_EXPLICIT, HarmBlockThreshold.MEDIUM_AND_ABOVE),
                SafetySetting(HarmCategory.DANGEROUS_CONTENT, HarmBlockThreshold.MEDIUM_AND_ABOVE),
            ),
            systemInstruction = content {
                text("""You are a friendly assistant. Keep your responses short.""")
            },
        )

Here is the key snippet of code that calls the generative model:

val content = content {
    text(message)
    if (bitmap != null) {
        image(bitmap)
    }
}
val response = chat.sendMessage(content)

Read more about image generation with Gemini in the Android Documentation.