Use Nano Banana in Python

NanoBanana-Python.md

Using Nano Banana with Python

Guide on how to use Nano Banana aka Gemini 2.5 Flash Image in Python with the Google GenAI SDK.

A detailed blog post can be found on TBD.

More resources:

• Get an API key from Google AI Studio.
• Nano Banana Gemini API docs

Installation

Install the SDK and Pillow (Pillow is used for image manipulation):

pip install -U google-genai
pip install Pillow

Image Generation from Text

from google import genai
from PIL import Image
from io import BytesIO

# Configure the client with your API key
client = genai.Client(api_key="YOUR_API_KEY")

prompt = """Create a photorealistic image of an orange cat
with a green eyes, sitting on a couch."""

# Call the API to generate content
response = client.models.generate_content(
    model="gemini-2.5-flash-image-preview",
    contents=prompt,
)

# The response can contain both text and image data.
# Iterate through the parts to find and save the image.
for part in response.candidates[0].content.parts:
    if part.text is not None:
        print(part.text)
    elif part.inline_data is not None:
        image = Image.open(BytesIO(part.inline_data.data))
        image.save("cat.png")

Image Editing with Text and Image Inputs

from google import genai
from PIL import Image
from io import BytesIO

client = genai.Client(api_key="YOUR_API_KEY")

prompt = """Using the image of the cat, create a photorealistic,
street-level view of the cat walking along a sidewalk in a
New York City neighborhood, with the blurred legs of pedestrians
and yellow cabs passing by in the background."""

image = Image.open("cat.png")

# Pass both the text prompt and the image in the 'contents' list
response = client.models.generate_content(
    model="gemini-2.5-flash-image-preview",
    contents=[prompt, image],
)

for part in response.candidates[0].content.parts:
    if part.text is not None:
        print(part.text)
    elif part.inline_data is not None:
        image = Image.open(BytesIO(part.inline_data.data))
        image.save("cat2.png")

Photo restoration with Nano Banana

from google import genai
from PIL import Image
from io import BytesIO

client = genai.Client(api_key="YOUR_API_KEY")

prompt = "Restore and colorize this image from 1932"

image = Image.open("lunch.jpg")  # "Lunch atop a Skyscraper, 1932"

response = client.models.generate_content(
    model="gemini-2.5-flash-image-preview",
    contents=[prompt, image],
)

for part in response.candidates[0].content.parts:
    if part.text is not None:
        print(part.text)
    elif part.inline_data is not None:
        image = Image.open(BytesIO(part.inline_data.data))
        image.save("lunch-restored.png")

Working with Multiple Input Images

from google import genai
from PIL import Image
from io import BytesIO

client = genai.Client(api_key="YOUR_API_KEY")

prompt = "Make the girl wear this t-shirt. Leave the background unchanged."

image1 = Image.open("girl.png")
image2 = Image.open("tshirt.png")

response = client.models.generate_content(
    model="gemini-2.5-flash-image-preview",
    contents=[prompt, image1, image2],
)

for part in response.candidates[0].content.parts:
    if part.text is not None:
        print(part.text)
    elif part.inline_data is not None:
        image = Image.open(BytesIO(part.inline_data.data))
        image.save("girl-with-shirt.png")

Conversational Image Editing

from google import genai
from PIL import Image
from io import BytesIO

client = genai.Client(api_key="YOUR_API_KEY")

# Create a chat
chat = client.chats.create(
    model="gemini-2.5-flash-image-preview"
)

# Make the first image edit
response1 = chat.send_message(
    [
        "Change the cat to a bengal cat, leave everything else the same",
        Image.open("cat.png"),
    ]
)

# display / save image...

# Continue chatting and editing
response2 = chat.send_message("The cat should wear a funny party hat")
# display / save image...