Image generation with Gemini (aka Nano Banana) via JavaScript

Gemini can generate and process images conversationally. You can prompt Gemini with text, images, or a combination of both allowing you to create, edit, and iterate on visuals with unprecedented control:

• Text-to-Image: Generate high-quality images from simple or complex text descriptions.
• Image + Text-to-Image (Editing): Provide an image and use text prompts to add, remove, or modify elements, change the style, or adjust the color grading.
• Multi-Image to Image (Composition & Style Transfer): Use multiple input images to compose a new scene or transfer the style from one image to another.
• Iterative Refinement: Engage in a conversation to progressively refine your image over multiple turns, making small adjustments until it's perfect.
• High-Fidelity Text Rendering: Accurately generate images that contain legible and well-placed text, ideal for logos, diagrams, and posters.

All generated images include a SynthID watermark.

Image generation (text-to-image)

The following code demonstrates how to generate an image based on a descriptive prompt.

import { GoogleGenAI, Modality } from "@google/genai";
import * as fs from "node:fs";

async function main() {
  const ai = new GoogleGenAI({});

  const prompt =
    "Create a picture of a nano banana dish in a fancy restaurant with a Gemini theme";

  const response = await ai.models.generateContent({
    model: "gemini-2.5-flash-image-preview",
    contents: prompt,
  });
  for (const part of response.candidates[0].content.parts) {
    if (part.text) {
      console.log(part.text);
    } else if (part.inlineData) {
      const imageData = part.inlineData.data;
      const buffer = Buffer.from(imageData, "base64");
      fs.writeFileSync("gemini-native-image.png", buffer);
      console.log("Image saved as gemini-native-image.png");
    }
  }
}

main();

AI-generated image of a nano banana dish in a Gemini-themed restaurant

Image editing (text-and-image-to-image)

Reminder: Make sure you have the necessary rights to any images you upload. Don't generate content that infringe on others' rights, including videos or images that deceive, harass, or harm. Your use of this generative AI service is subject to our Prohibited Use Policy.

The following example demonstrates uploading base64 encoded images. For multiple images, larger payloads, and supported MIME types, check the Image understanding page.

import { GoogleGenAI, Modality } from "@google/genai";
import * as fs from "node:fs";

async function main() {
  const ai = new GoogleGenAI({});

  const imagePath = "path/to/cat_image.png";
  const imageData = fs.readFileSync(imagePath);
  const base64Image = imageData.toString("base64");

  const prompt = [
    {
      text:
        "Create a picture of my cat eating a nano-banana in a" +
        "fancy restaurant under the Gemini constellation",
    },
    {
      inlineData: {
        mimeType: "image/png",
        data: base64Image,
      },
    },
  ];

  const response = await ai.models.generateContent({
    model: "gemini-2.5-flash-image-preview",
    contents: prompt,
  });
  for (const part of response.candidates[0].content.parts) {
    if (part.text) {
      console.log(part.text);
    } else if (part.inlineData) {
      const imageData = part.inlineData.data;
      const buffer = Buffer.from(imageData, "base64");
      fs.writeFileSync("gemini-native-image.png", buffer);
      console.log("Image saved as gemini-native-image.png");
    }
  }
}

main();

AI-generated image of a cat eating a nano banana

Other image generation modes

Gemini supports other image interaction modes based on prompt structure and context, including:

• Text to image(s) and text (interleaved): Outputs images with related text.
  • Example prompt: "Generate an illustrated recipe for a paella."
• Image(s) and text to image(s) and text (interleaved): Uses input images and text to create new related images and text.
  • Example prompt: (With an image of a furnished room) "What other color sofas would work in my space? can you update the image?"
• Multi-turn image editing (chat): Keep generating and editing images conversationally.
  • Example prompts: [upload an image of a blue car.] , "Turn this car into a convertible.", "Now change the color to yellow."

Prompting guide and strategies

Mastering Gemini 2.5 Flash Image Generation starts with one fundamental principle:

Describe the scene, don't just list keywords. The model's core strength is its deep language understanding. A narrative, descriptive paragraph will almost always produce a better, more coherent image than a list of disconnected words.

Prompts for generating images

The following strategies will help you create effective prompts to generate exactly the images you're looking for.

1. Photorealistic scenes

For realistic images, use photography terms. Mention camera angles, lens types, lighting, and fine details to guide the model toward a photorealistic result.

import { GoogleGenAI, Modality } from "@google/genai";
import * as fs from "node:fs";

async function main() {
  const ai = new GoogleGenAI({});

  const prompt =
    "A photorealistic close-up portrait of an elderly Japanese ceramicist with deep, sun-etched wrinkles and a warm, knowing smile. He is carefully inspecting a freshly glazed tea bowl. The setting is his rustic, sun-drenched workshop with pottery wheels and shelves of clay pots in the background. The scene is illuminated by soft, golden hour light streaming through a window, highlighting the fine texture of the clay and the fabric of his apron. Captured with an 85mm portrait lens, resulting in a soft, blurred background (bokeh). The overall mood is serene and masterful.";

  const response = await ai.models.generateContent({
    model: "gemini-2.5-flash-image-preview",
    contents: prompt,
  });
  for (const part of response.candidates[0].content.parts) {
    if (part.text) {
      console.log(part.text);
    } else if (part.inlineData) {
      const imageData = part.inlineData.data;
      const buffer = Buffer.from(imageData, "base64");
      fs.writeFileSync("photorealistic_example.png", buffer);
      console.log("Image saved as photorealistic_example.png");
    }
  }
}

main();

A photorealistic close-up portrait of an elderly Japanese ceramicist...

2. Stylized illustrations & stickers

To create stickers, icons, or assets, be explicit about the style and request a transparent background.

import { GoogleGenAI, Modality } from "@google/genai";
import * as fs from "node:fs";

async function main() {
  const ai = new GoogleGenAI({});

  const prompt =
    "A kawaii-style sticker of a happy red panda wearing a tiny bamboo hat. It's munching on a green bamboo leaf. The design features bold, clean outlines, simple cel-shading, and a vibrant color palette. The background must be white.";

  const response = await ai.models.generateContent({
    model: "gemini-2.5-flash-image-preview",
    contents: prompt,
  });
  for (const part of response.candidates[0].content.parts) {
    if (part.text) {
      console.log(part.text);
    } else if (part.inlineData) {
      const imageData = part.inlineData.data;
      const buffer = Buffer.from(imageData, "base64");
      fs.writeFileSync("red_panda_sticker.png", buffer);
      console.log("Image saved as red_panda_sticker.png");
    }
  }
}

main();

A kawaii-style sticker of a happy red panda...

3. Accurate text in images

Gemini excels at rendering text. Be clear about the text, the font style (descriptively), and the overall design.

import { GoogleGenAI, Modality } from "@google/genai";
import * as fs from "node:fs";

async function main() {
  const ai = new GoogleGenAI({});

  const prompt =
    "Create a modern, minimalist logo for a coffee shop called 'The Daily Grind'. The text should be in a clean, bold, sans-serif font. The design should feature a simple, stylized icon of a a coffee bean seamlessly integrated with the text. The color scheme is black and white.";

  const response = await ai.models.generateContent({
    model: "gemini-2.5-flash-image-preview",
    contents: prompt,
  });
  for (const part of response.candidates[0].content.parts) {
    if (part.text) {
      console.log(part.text);
    } else if (part.inlineData) {
      const imageData = part.inlineData.data;
      const buffer = Buffer.from(imageData, "base64");
      fs.writeFileSync("logo_example.png", buffer);
      console.log("Image saved as logo_example.png");
    }
  }
}

main();

Create a modern, minimalist logo for a coffee shop called 'The Daily Grind'...

4. Product mockups & commercial photography

Perfect for creating clean, professional product shots for e-commerce, advertising, or branding.

import { GoogleGenAI, Modality } from "@google/genai";
import * as fs from "node:fs";

async function main() {
  const ai = new GoogleGenAI({});

  const prompt =
    "A high-resolution, studio-lit product photograph of a minimalist ceramic coffee mug in matte black, presented on a polished concrete surface. The lighting is a three-point softbox setup designed to create soft, diffused highlights and eliminate harsh shadows. The camera angle is a slightly elevated 45-degree shot to showcase its clean lines. Ultra-realistic, with sharp focus on the steam rising from the coffee. Square image.";

  const response = await ai.models.generateContent({
    model: "gemini-2.5-flash-image-preview",
    contents: prompt,
  });
  for (const part of response.candidates[0].content.parts) {
    if (part.text) {
      console.log(part.text);
    } else if (part.inlineData) {
      const imageData = part.inlineData.data;
      const buffer = Buffer.from(imageData, "base64");
      fs.writeFileSync("product_mockup.png", buffer);
      console.log("Image saved as product_mockup.png");
    }
  }
}

main();

A high-resolution, studio-lit product photograph of a minimalist ceramic coffee mug...

5. Minimalist & negative space design

Excellent for creating backgrounds for websites, presentations, or marketing materials where text will be overlaid.

import { GoogleGenAI, Modality } from "@google/genai";
import * as fs from "node:fs";

async function main() {
  const ai = new GoogleGenAI({});

  const prompt =
    "A minimalist composition featuring a single, delicate red maple leaf positioned in the bottom-right of the frame. The background is a vast, empty off-white canvas, creating significant negative space for text. Soft, diffused lighting from the top left. Square image.";

  const response = await ai.models.generateContent({
    model: "gemini-2.5-flash-image-preview",
    contents: prompt,
  });
  for (const part of response.candidates[0].content.parts) {
    if (part.text) {
      console.log(part.text);
    } else if (part.inlineData) {
      const imageData = part.inlineData.data;
      const buffer = Buffer.from(imageData, "base64");
      fs.writeFileSync("minimalist_design.png", buffer);
      console.log("Image saved as minimalist_design.png");
    }
  }
}

main();

A minimalist composition featuring a single, delicate red maple leaf...

6. Sequential art (Comic panel / Storyboard)

Builds on character consistency and scene description to create panels for visual storytelling.

import { GoogleGenAI, Modality } from "@google/genai";
import * as fs from "node:fs";

async function main() {
  const ai = new GoogleGenAI({});

  const prompt =
    "A single comic book panel in a gritty, noir art style with high-contrast black and white inks. In the foreground, a detective in a trench coat stands under a flickering streetlamp, rain soaking his shoulders. In the background, the neon sign of a desolate bar reflects in a puddle. A caption box at the top reads \"The city was a tough place to keep secrets.\" The lighting is harsh, creating a dramatic, somber mood. Landscape.";

  const response = await ai.models.generateContent({
    model: "gemini-2.5-flash-image-preview",
    contents: prompt,
  });
  for (const part of response.candidates[0].content.parts) {
    if (part.text) {
      console.log(part.text);
    } else if (part.inlineData) {
      const imageData = part.inlineData.data;
      const buffer = Buffer.from(imageData, "base64");
      fs.writeFileSync("comic_panel.png", buffer);
      console.log("Image saved as comic_panel.png");
    }
  }
}

main();

A single comic book panel in a gritty, noir art style...

Prompts for editing images

These examples show how to provide images alongside your text prompts for editing, composition, and style transfer.

1. Adding and removing elements

Provide an image and describe your change. The model will match the original image's style, lighting, and perspective.

import { GoogleGenAI, Modality } from "@google/genai";
import * as fs from "node:fs";

async function main() {
  const ai = new GoogleGenAI({});

  const imagePath = "/path/to/your/cat_photo.png";
  const imageData = fs.readFileSync(imagePath);
  const base64Image = imageData.toString("base64");

  const prompt = [
    {
      text:
        "Using the provided image of my cat, please add a small, knitted wizard hat on its head. Make it look like it's sitting comfortably and not falling off.",
    },
    {
      inlineData: {
        mimeType: "image/png",
        data: base64Image,
      },
    },
  ];

  const response = await ai.models.generateContent({
    model: "gemini-2.5-flash-image-preview",
    contents: prompt,
  });
  for (const part of response.candidates[0].content.parts) {
    if (part.text) {
      console.log(part.text);
    } else if (part.inlineData) {
      const imageData = part.inlineData.data;
      const buffer = Buffer.from(imageData, "base64");
      fs.writeFileSync("cat_with_hat.png", buffer);
      console.log("Image saved as cat_with_hat.png");
    }
  }
}

main();

Input

A photorealistic picture of a fluffy ginger cat...

Output

Using the provided image of my cat, please add a small, knitted wizard hat...

2. Inpainting (Semantic masking)

Conversationally define a "mask" to edit a specific part of an image while leaving the rest untouched.

import { GoogleGenAI, Modality } from "@google/genai";
import * as fs from "node:fs";

async function main() {
  const ai = new GoogleGenAI({});

  const imagePath = "/path/to/your/living_room.png";
  const imageData = fs.readFileSync(imagePath);
  const base64Image = imageData.toString("base64");

  const prompt = [
    {
      inlineData: {
        mimeType: "image/png",
        data: base64Image,
      },
    },
    {
      text:
        "Using the provided image of a living room, change only the blue sofa to be a vintage, brown leather chesterfield sofa. Keep the rest of the room, including the pillows on the sofa and the lighting, unchanged.",
    },
  ];

  const response = await ai.models.generateContent({
    model: "gemini-2.5-flash-image-preview",
    contents: prompt,
  });
  for (const part of response.candidates[0].content.parts) {
    if (part.text) {
      console.log(part.text);
    } else if (part.inlineData) {
      const imageData = part.inlineData.data;
      const buffer = Buffer.from(imageData, "base64");
      fs.writeFileSync("living_room_edited.png", buffer);
      console.log("Image saved as living_room_edited.png");
    }
  }
}

main();

Input

A wide shot of a modern, well-lit living room...

Output

Using the provided image of a living room, change only the blue sofa to be a vintage, brown leather chesterfield sofa...

3. Style transfer

Provide an image and ask the model to recreate its content in a different artistic style.

import { GoogleGenAI, Modality } from "@google/genai";
import * as fs from "node:fs";

async function main() {
  const ai = new GoogleGenAI({});

  const imagePath = "/path/to/your/city.png";
  const imageData = fs.readFileSync(imagePath);
  const base64Image = imageData.toString("base64");

  const prompt = [
    {
      inlineData: {
        mimeType: "image/png",
        data: base64Image,
      },
    },
    {
      text:
        "Transform the provided photograph of a modern city street at night into the artistic style of Vincent van Gogh's 'Starry Night'. Preserve the original composition of buildings and cars, but render all elements with swirling, impasto brushstrokes and a dramatic palette of deep blues and bright yellows.",
    },
  ];

  const response = await ai.models.generateContent({
    model: "gemini-2.5-flash-image-preview",
    contents: prompt,
  });
  for (const part of response.candidates[0].content.parts) {
    if (part.text) {
      console.log(part.text);
    } else if (part.inlineData) {
      const imageData = part.inlineData.data;
      const buffer = Buffer.from(imageData, "base64");
      fs.writeFileSync("city_style_transfer.png", buffer);
      console.log("Image saved as city_style_transfer.png");
    }
  }
}

main();

Input

A photorealistic, high-resolution photograph of a busy city street...

Output

Transform the provided photograph of a modern city street at night...

4. Advanced composition: Combining multiple images

Provide multiple images as context to create a new, composite scene. This is perfect for product mockups or creative collages.

import { GoogleGenAI, Modality } from "@google/genai";
import * as fs from "node:fs";

async function main() {
  const ai = new GoogleGenAI({});

  const imagePath1 = "/path/to/your/dress.png";
  const imageData1 = fs.readFileSync(imagePath1);
  const base64Image1 = imageData1.toString("base64");
  const imagePath2 = "/path/to/your/model.png";
  const imageData2 = fs.readFileSync(imagePath2);
  const base64Image2 = imageData2.toString("base64");

  const prompt = [
    {
      inlineData: {
        mimeType: "image/png",
        data: base64Image1,
      },
    },
    {
      inlineData: {
        mimeType: "image/png",
        data: base64Image2,
      },
    },
    {
      text:
        "Create a professional e-commerce fashion photo. Take the blue floral dress from the first image and let the woman from the second image wear it. Generate a realistic, full-body shot of the woman wearing the dress, with the lighting and shadows adjusted to match the outdoor environment.",
    },
  ];

  const response = await ai.models.generateContent({
    model: "gemini-2.5-flash-image-preview",
    contents: prompt,
  });
  for (const part of response.candidates[0].content.parts) {
    if (part.text) {
      console.log(part.text);
    } else if (part.inlineData) {
      const imageData = part.inlineData.data;
      const buffer = Buffer.from(imageData, "base64");
      fs.writeFileSync("fashion_ecommerce_shot.png", buffer);
      console.log("Image saved as fashion_ecommerce_shot.png");
    }
  }
}

main();

Input 1

A professionally shot photo of a blue floral summer dress...

Input 2

Full-body shot of a woman with her hair in a bun...

Output

Create a professional e-commerce fashion photo...

5. High-fidelity detail preservation

To ensure critical details (like a face or logo) are preserved during an edit, describe them in great detail along with your edit request.

import { GoogleGenAI, Modality } from "@google/genai";
import * as fs from "node:fs";

async function main() {
  const ai = new GoogleGenAI({});

  const imagePath1 = "/path/to/your/woman.png";
  const imageData1 = fs.readFileSync(imagePath1);
  const base64Image1 = imageData1.toString("base64");
  const imagePath2 = "/path/to/your/logo.png";
  const imageData2 = fs.readFileSync(imagePath2);
  const base64Image2 = imageData2.toString("base64");

  const prompt = [
    {
      inlineData: {
        mimeType: "image/png",
        data: base64Image1,
      },
    },
    {
      inlineData: {
        mimeType: "image/png",
        data: base64Image2,
      },
    },
    {
      text:
        "Take the first image of the woman with brown hair, blue eyes, and a neutral expression. Add the logo from the second image onto her black t-shirt. Ensure the woman's face and features remain completely unchanged. The logo should look like it's naturally printed on the fabric, following the folds of the shirt.",
    },
  ];

  const response = await ai.models.generateContent({
    model: "gemini-2.5-flash-image-preview",
    contents: prompt,
  });
  for (const part of response.candidates[0].content.parts) {
    if (part.text) {
      console.log(part.text);
    } else if (part.inlineData) {
      const imageData = part.inlineData.data;
      const buffer = Buffer.from(imageData, "base64");
      fs.writeFileSync("woman_with_logo.png", buffer);
      console.log("Image saved as woman_with_logo.png");
    }
  }
}

main();

Input 1

A professional headshot of a woman with brown hair and blue eyes...

Input 2

A simple, modern logo with the letters 'G' and 'A'...

Output

Take the first image of the woman with brown hair, blue eyes, and a neutral expression...

Best Practices

To elevate your results from good to great, incorporate these professional strategies into your workflow.

• Be Hyper-Specific: The more detail you provide, the more control you have. Instead of "fantasy armor," describe it: "ornate elven plate armor, etched with silver leaf patterns, with a high collar and pauldrons shaped like falcon wings."
• Provide Context and Intent: Explain the purpose of the image. The model's understanding of context will influence the final output. For example, "Create a logo for a high-end, minimalist skincare brand" will yield better results than just "Create a logo."
• Iterate and Refine: Don't expect a perfect image on the first try. Use the conversational nature of the model to make small changes. Follow up with prompts like, "That's great, but can you make the lighting a bit warmer?" or "Keep everything the same, but change the character's expression to be more serious."
• Use Step-by-Step Instructions: For complex scenes with many elements, break your prompt into steps. "First, create a background of a serene, misty forest at dawn. Then, in the foreground, add a moss-covered ancient stone altar. Finally, place a single, glowing sword on top of the altar."
• Use "Semantic Negative Prompts": Instead of saying "no cars," describe the desired scene positively: "an empty, deserted street with no signs of traffic."
• Control the Camera: Use photographic and cinematic language to control the composition. Terms like wide-angle shot, macro shot, low-angle perspective.

Limitations

• For best performance, use the following languages: EN, es-MX, ja-JP, zh-CN, hi-IN.
• Image generation does not support audio or video inputs.
• The model won't always follow the exact number of image outputs that the user explicitly asked for.
• The model works best with up to 3 images as an input.
• When generating text for an image, Gemini works best if you first generate the text and then ask for an image with the text.
• Uploading images of children is not currently supported in EEA, CH, and UK.
• All generated images include a SynthID watermark.

When to use Imagen

In addition to using Gemini's built-in image generation capabilities, you can also access Imagen, our specialized image generation model, through the Gemini API.

• Image quality, photorealism, artistic detail, or specific styles (e.g., impressionism, anime) are top priorities.
• Infusing branding, style, or generating logos and product designs.
• Generating advanced spelling or typography.
• Interleaved text and image generation to seamlessly blend text and images.
• Combine creative elements from multiple images with a single prompt.
• Make highly specific edits to images, modify individual elements with simple language commands, and iteratively work on an image.
• Apply a specific design or texture from one image to another while preserving the original subject's form and details.

|

Imagen 4 should be your go-to model for generating images. Choose Imagen 4 Ultra for advanced use cases or when you need the best image quality (note that it can only generate one image at a time).