Image Extender

What does this tool do?

Image Extender (also called an outpainter or uncropper) widens or heightens any photo to a new aspect ratio without losing a single original pixel. Drop a 4:3 shot, ask for 16:9, and the borders are filled in with one of five algorithms instead of being cropped off.

This is the daily workflow for social-media managers, product photographers, real-estate agents, designers, and anyone whose phone takes 4:3 photos but the platform wants 16:9 or 1:1. Resizing alone distorts the subject; cropping alone loses the edges; this tool adds pixels where they belong.

How it works

1. Upload any JPG, PNG, WebP or BMP up to 20 MB.
2. Pick target size: type W x H manually, lock the aspect ratio you want, or click a preset (1:1, 16:9, 9:16, 21:9, Instagram, YouTube…).
3. Pick a fill algorithm (Mirror Reflect, Edge Blur Extend, Seamless Repeat, Linear Stretch or Solid Color) and tweak the feather/colour as needed.
4. Click Extend Image — 100% browser Canvas processing, no upload to any server.
5. Compare original vs extended side-by-side, then download PNG/JPG/WebP.

Fill algorithms explained

• Mirror Reflect — the original image stays untouched in the centre; the new border is a literal mirror of the near edge with an adjustable feather seam. Excellent for portraits, symmetric compositions and product shots. Adaptive when the border is wide.
• Edge Blur Extend — computes a gradient halo from the existing edge pixels, blurred and blended across the new border. No visible seam. Best general-purpose mode for landscapes, casual photos and screenshots.
• Seamless Repeat — tiles the outermost edge column/row outward, then feathers it into the original. Best when the photo already looks like part of a pattern (sky, fabric, paper, gradient).
• Linear Stretch — stretches the outermost edge column/row outward with linear interpolation. Simplest, fastest, lowest quality — good when you plan to overlay other content (text, banners) on top.
• Solid Color — flat colour or transparent fill picked via the colour picker or transparent checkbox. Best for banners, branded exports and design assets where the border is part of the composition.

Why use this instead of an AI outpainting service?

• Free, no signup, no watermarks, no daily limits. Adobe Firefly ($20/mo), Canva Pro ($13/mo), Pixa.ai, Fotor, Pixelcut all charge or limit free users; require account creation; and cap monthly generations.
• 100% private. Your photo never leaves the browser. No server upload, no training pipeline, no analytics on your content.
• Deterministic. Same image + same settings = same output. Perfect for product listings that must be reproducible across sessions.
• Five fill modes in one tool. Most AI services only offer one; we ship mirror, blur, repeat, stretch and solid so you can pick the one that fits the photo.
• Works offline. Once the page is loaded, no further network is needed.

Common use cases

• Social media reformatting. Reshoot a 4:3 phone photo to 9:16 Stories, 1:1 Instagram square, 16:9 YouTube thumb — no crop.
• Print borders. Add a uniform coloured border to a print job without resizing the photo itself.
• Banner generation. Turn a square logo into a 21:9 website header by extending the background.
• eBay / Etsy / Amazon listings. White-extend a product photo to fit marketplace recommended aspect ratios (white background is part of the listing rules).
• Design asset prep. Give an icon extra padding canvas so designers can drop it into any layout.

Frequently asked questions

What does this image extender do?

It expands the canvas of a photo to a new aspect ratio (for example 4:3 to 16:9) without cropping any of the original content. Five fill algorithms generate the new border pixels. Useful for social media reformatting, print borders, banners and uncropping narrow photos.

Is my image uploaded to any server?

No. Everything runs in your browser via the Canvas API. Your image never leaves your device. AI chatbots (ChatGPT, Claude, Gemini) cannot replicate this because they have no pixel-level image editing pipeline in their chat interface.

Which fill algorithm should I choose?

Mirror Reflect for portraits and symmetric subjects. Edge Blur Extend for general photos (smooth, no visible seam). Seamless Repeat for textures and patterns. Linear Stretch for landscapes. Solid Color for banners where the border colour is part of the design.

What aspect ratios are supported?

Free-form W x H (up to 8000 x 8000) plus presets: 1:1, 4:3, 3:2, 16:9, 21:9, 9:16, 4:5, 2:3 and social media sizes for Instagram square, Instagram portrait, Facebook cover, Twitter header, LinkedIn banner, YouTube thumbnail and Full HD.

How is this different from the Image Upscaler?

Image Upscaler enlarges the entire image proportionally (every pixel grows). Image Extender keeps the original photo pixel-for-pixel and only adds new pixels to the borders. Use Upscaler for higher resolution; use Extender for a different aspect ratio without losing content.

Why do AI chatbots fail at this?

AI chatbots (ChatGPT, Claude, Gemini) have no native image editing pipeline. They cannot read JPEG metadata, blend pixel rows across an arbitrary seam or output a valid PNG. This tool runs the deterministic pixel blend in your browser with one click.

What is the maximum output size?

Target W x H is capped at 8000 x 8000 pixels (browser Canvas memory). Most phones and laptops handle 6000 x 6000 easily. Close other tabs and use a recent Chrome, Edge, Firefox or Safari for large outputs.

Can I export transparent borders?

Yes. Pick PNG output and check Solid Color fill, then tick Transparent. The result keeps the original photo pixels unchanged and adds new transparent pixels around it. Most useful for design workflows that need source assets with extra canvas.