For most website images created or edited in Python, start with Pillow. It creates and processes raster images such as PNGs, composites and thumbnails. Choose CairoSVG when your input is SVG artwork that needs conversion to PNG or another supported output. They do different jobs, and can be used together when an SVG needs raster post-processing.
Choose the package by the image workflow
| What you need to do | Good starting point | Check before shipping |
|---|---|---|
| Create or manipulate raster images, thumbnails, or composites | Pillow | Required format support, installed build dependencies, input size limits, and output encoding needs |
| Convert SVG artwork to PNG, PDF, PS, or SVG | CairoSVG | SVG feature coverage, Cairo/FFI dependencies, deployment platform, and license obligations |
| Convert an SVG, then edit the resulting pixels | CairoSVG and, if needed, Pillow | Validate the output and the dependencies of both packages in your target environment |
This is a practical division of labor, not a performance ranking. Pillow is a general raster-image library; CairoSVG converts SVG documents. Neither is established as the universal best package for every website-image task.
Create website raster images with Pillow
Pillow is the maintained fork of PIL and provides a broad image-processing API. Use it to make a canvas, draw or composite image content, resize an existing raster, create a thumbnail, or save a supported format. It can also generate effects such as gradients and noise. The library handles pixels and file encoding; it does not make design decisions or provide a complete image-delivery service.
Install and create a PNG
Install Pillow in the Python environment that runs your script:
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
#1 Best Overall
python -m pip install PillowThis example creates a simple 640-by-360 RGB image and writes it as a PNG:
from PIL import Image, ImageDraw
image = Image.new("RGB", (640, 360), color="#f2f5f9")
draw = ImageDraw.Draw(image)
draw.rectangle((32, 32, 608, 328), fill="#174ea6")
draw.text((56, 72), "Generated with Pillow", fill="white")
image.save("website-card.png", format="PNG")The dimensions are pixels, and the explicit format makes the intended encoding clear. For transparency, create an image in an alpha-capable mode such as RGBA and save to a format that supports alpha, such as PNG or WebP where available in the installed build.
Resize, thumbnail, and composite
For an existing image, open it, convert to a mode suitable for the operation, and resize or composite it. Pillow’s thumbnail workflow preserves aspect ratio while fitting within a bounding box:
from PIL import Image
with Image.open("source.jpg") as source:
source.thumbnail((800, 800))
source.convert("RGB").save("thumbnail.jpg", format="JPEG", quality=85)Unlike a fixed-size resize, thumbnail constrains the image to the requested box without enlarging it beyond its original size. JPEG has no transparency, so converting to RGB is appropriate when the output is a JPEG. Use an alpha-capable output if transparent areas must remain transparent.
Recommended Free Tools
For images generated in memory rather than saved directly to disk, Pillow supports file-like objects. A BytesIO buffer is useful when an application needs encoded bytes for another layer of its own response or storage workflow:
from io import BytesIO
from PIL import Image
image = Image.new("RGB", (320, 180), "white")
buffer = BytesIO()
image.save(buffer, format="PNG")
png_bytes = buffer.getvalue()The buffer contains encoded image data; your web framework still needs to set the appropriate response content type and handle delivery.
Confirm formats in the deployed build
Do not assume every Pillow installation supports every image format identically. Consult the format handbook and verify the exact format support and system dependencies in the environment where the application will run. A script that works on a developer workstation can fail in a different deployment image if its installed build differs.
Convert SVG artwork with CairoSVG
SVG is vector artwork; a website workflow may need a raster PNG, or another output CairoSVG supports. CairoSVG is a Python 3 library and command-line tool for converting SVG 1.1 documents to PNG, PDF, PS, or SVG. It exposes Python functions such as svg2png and a CLI for file conversion.
Install and convert from Python
The package name for pip installation is cairosvg:
python -m pip install cairosvgFor an SVG file named logo.svg, a basic Python conversion is:
import cairosvg
cairosvg.svg2png(url="logo.svg", write_to="logo.png")You can also invoke the command-line converter:
cairosvg logo.svg -o logo.pngUse the output type and options documented by CairoSVG for the target task. A simple conversion does not guarantee that every SVG feature will render exactly as it does in every browser or design tool.
Check platform dependencies, feature coverage, and licensing
CairoSVG documentation lists Linux, macOS, and Windows support, but installation can involve native components, including Cairo and FFI headers, and platform-specific setup. Confirm its current installation instructions for the operating system and deployment image you use rather than treating pip installation alone as proof that all dependencies are present.
Its documented SVG support has limitations: ICC color schemes, color interpolation and gamma correction for external raster images, and some SVG filters are not fully supported. Test representative artwork—especially assets using filters or color-management features—in the actual deployment environment. The documentation describes CairoSVG as LGPLv3 licensed; review the license terms for your distribution model.
Quick wins for a faster PC:
Clear out junk files and repair common Windows errorsFree Scan →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Repair Windows errors before they cause bigger problemsFix Now →Use both when a workflow crosses vector and raster
If the source is SVG but later operations are pixel-based, convert with CairoSVG first and then open the PNG with Pillow. This keeps each step aligned to the package's documented role:
import cairosvg
from PIL import Image
cairosvg.svg2png(url="icon.svg", write_to="icon.png")
with Image.open("icon.png") as image:
image.thumbnail((256, 256))
image.save("icon-small.png", format="PNG")This two-package example writes an intermediate file for clarity. A production pipeline can use in-memory streams if desired, but should still validate the rendered result and both packages' runtime dependencies.
Protect image-processing applications from risky inputs
If your application accepts images from users, treat decoding as work on untrusted input. Pillow documents a decompression-bomb warning and error behavior: a compact file can expand into a very large pixel image and consume excessive memory. Pillow uses a pixel-count threshold to detect this risk. Do not disable that safeguard casually; doing so removes a protection against oversized or hostile images. Set application-level upload and resource limits appropriate to your service, and decide deliberately how warnings and errors are handled.
Also validate expected formats and dimensions at the boundary of the application, and test failure handling with the same Pillow build used in production. Format support and behavior can depend on the installed build, so do not rely on assumptions based only on a developer machine.
Troubleshoot common failures
ModuleNotFoundErrorforPILorcairosvg: Install the package into the same Python interpreter or virtual environment that runs the program. Pillow is installed asPillowbut imported fromPIL; CairoSVG is installed ascairosvg.- CairoSVG install or import fails: Check the operating-system-specific Cairo and FFI requirements in its documentation. A Python package install may also need native libraries or build components.
- An SVG looks different after conversion: Check whether the artwork uses features CairoSVG documents as limited, including some filters or color-management behavior. Test and, if necessary, revise or simplify the source SVG.
- An image format cannot be opened or saved: Verify that the deployed Pillow build supports that format and has its required dependencies. Use the format handbook to check the format rather than assuming all builds are alike.
- Large or untrusted input triggers a warning or error: Pillow's decompression-bomb protection is signaling a potentially resource-heavy image. Review the input limits and handling policy; do not switch off the protection without understanding the risk.
- Generated output has unexpected transparency or color: Confirm the image mode and output format. For example, JPEG cannot preserve alpha transparency; choose an alpha-capable output when transparent pixels matter.
Capture a web page instead of generating an image
Pillow and CairoSVG create or convert image assets; they are not browser screenshot tools. If the actual task is to render a live web page and save what a visitor sees, you need a browser-based capture workflow rather than a raster drawing API.
Or skip the browser setup
ScreenshotNeo is a website screenshot API and MCP server for developers. A single GET request can return a PNG, JPEG, WebP, or PDF. Here is the cURL call, with the API details in the ScreenshotNeo documentation:
curl -G "https://api.screenshotneo.com/v1/shot" -d access_key=YOUR_API_KEY --data-urlencode url=https://stripe.com -o shot.webpCookie banners are accepted like a visitor and removed, along with supported newsletter popups and chat widgets, before capture; each cleanup step can be turned off. Bot checks, blank pages, failed loads, timeouts, and cache hits cost nothing, and response headers identify the page verdict and billing status. Its MCP server lets AI agents using Claude, Cursor, or another MCP client take screenshots. The free plan includes 1,000 shots per month with no card; paid plans start at $5 for 3,000 shots.
Sign up free for 1,000 screenshots a month, with no card required.
Frequently Asked Questions
Can Python generate a PNG for a website?
Yes. Pillow can create a raster canvas and save it as PNG; CairoSVG can convert an SVG document to PNG.
Do I need Pillow to convert SVG to PNG?
No. CairoSVG is specifically documented for SVG conversion; Pillow is useful for raster processing after conversion.
Can I use Pillow and CairoSVG together?
Yes. Convert the SVG to a raster image with CairoSVG, then use Pillow for pixel operations such as resizing or compositing.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
The Tool Desk
Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →
