What is a smart resize API?

A smart resize API is a web service that resizes images to a target aspect ratio and resolution without distortion or cropping. Instead of stretching the subject or cropping content out of the frame, the API uses generative reframing to add scene-matched pixels around the subject so the result fits the new canvas naturally. Used by ad teams, ecommerce brands, social platforms, and AI image products to ship one source across every channel format.

How is smart resize different from regular image resize?

Standard resize either scales the entire image (which distorts proportions when the target ratio differs from the source) or crops to fit the target ratio (which removes content). Smart Resize keeps the subject at correct proportions and generates new pixels in the canvas areas that need to be added, so a portrait can be reframed to landscape with the subject centered and the rest of the scene plausibly extended.

How is smart resize different from outpainting?

Outpainting takes per-side expansion parameters (e.g. 'add 200px top, 300px right') so you control exactly how the canvas extends. Smart Resize takes a target aspect ratio and resolution, and the API calculates the expansion automatically to hit that target while keeping the subject centered. Use Outpainting when you need precise per-side control. Use Smart Resize when you want a one-shot conversion to a named ratio plus resolution tier.

How does AI smart resize work?

The API analyzes the source image to locate the subject, then generates new pixels in the regions that need to be added to reach the target aspect ratio. The generated content matches the source scene's lighting, perspective, and style so the result looks like a wider or taller capture of the same moment. The output is rendered at your chosen resolution tier (1K, 2K, or 4K on the long side).

What aspect ratios are supported?

Eight target ratios: 1:1 (square), 16:9 (widescreen), 9:16 (vertical / Stories), 4:3 (standard), 3:4 (portrait), 21:9 (cinematic), 2:3 (portrait photo), 3:2 (landscape photo). Source images can be any starting ratio. The API computes the expansion required on each side to land on the target and centers the subject in the new canvas.

What resolution tiers are supported?

Three tiers, sized on the long side of the output: 1K (≈1024px), 2K (≈2048px), and 4K (≈4096px). Pick the tier that matches your destination format. Use 1K for previews and thumbnails, 2K for standard web and ad delivery, and 4K for print, hero shots, and high-DPI displays.

Does the subject stay intact in the output?

Yes. Smart Resize is designed so the subject's pixels and proportions are preserved. The API only generates new content in the canvas regions that need to be added to reach the target ratio. Critical for product photography, headshots, and editorial work where subject fidelity matters.

Does the generated content match the original scene?

Yes. The new pixels match the source image's style, lighting, texture, and perspective so the framing looks natural. The result reads as a wider, taller, or differently-shaped capture of the same moment, not a collage or a pasted background.

Do I need rights to the image I'm resizing?

Yes. You need rights to the source image: your own photography, licensed stock, or imagery you have permission to modify. The generated regions are derivative of your source (the AI uses your image's content and style to extend the canvas), so usage rights follow the source. For commercial use, prefer your own photography or properly licensed stock.

How much does the smart resize API cost?

$0.55 per image with simple fixed pricing, regardless of which aspect ratio or resolution you pick. Sign up and get $10 in free GPU credits to try it out. Contact us for volume pricing on bulk workloads.

Can I process images in bulk?

Yes. Batch endpoints with async webhook delivery. Process thousands of images per job with different aspect ratios and resolutions per image. Ideal for catalog adaptation, multi-format campaign rollouts, and content library normalization across an entire image library.

How fast is the smart resize API?

Typical response times scale with the chosen resolution tier. 1K outputs return in a few seconds, with 2K and 4K taking longer for the additional pixel generation. Built for production workloads with consistent latency at scale.

What image formats are supported?

JPEG, PNG, and WebP. Output format depends on the solution.

Typical response times are under 5 seconds for standard resolution images.

How does pricing work?

Simple fixed per-call pricing. No GPU costs, no infrastructure to maintain.

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One source image, every aspect ratio

Smart Resize API

Resize any image to a target aspect ratio and resolution (1K, 2K, 4K) without distortion or cropping. Generative reframing recomposes the subject into the new frame with one API call.

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Input

image_url *

Your request will cost $0.55

Output

Example output

Aspect ratios supported

$0.55

Per image, fixed pricing

Max output resolution

Batch

Bulk processing with webhooks

How it works

No pipeline to build, no models to configure.

Send image, aspect ratio, and resolution

Pull your source image and pick a target aspect ratio (1:1, 16:9, 9:16, 4:3, 3:4, 21:9, 2:3, 3:2) plus a resolution tier (1K, 2K, 4K).

AI recomposes the frame

Runflow's pipeline detects the subject, generates new pixels around it to match the target ratio, and outputs at the requested resolution. Subject stays intact, framing matches the new canvas.

Get your reframed image

Receive the resized image at your target ratio and resolution. Re-run with different aspect ratios to generate every format from one source. Each call is $0.55/image.

Reframe images without distortion or cropping

Traditional resize either crops the subject out or stretches it into a different shape. Smart Resize generates new pixels around the subject so the framing matches the target aspect ratio while the subject stays intact, properly proportioned, and centered in the new canvas.

No subject crops, no stretched proportions

Generative reframing fills the new canvas with scene-matched content

Subject stays intact, centered, and on-brand

Eight aspect ratios, three resolution tiers

Convert any source ratio to 1:1, 16:9, 9:16, 4:3, 3:4, 21:9, 2:3, or 3:2. Pick a resolution tier (1K, 2K, or 4K on the long side) so the same call produces output sized for your platform. One API, every format your channels need.

1:1, 16:9, 9:16, 4:3, 3:4, 21:9, 2:3, 3:2 supported

1K (1024px), 2K (2048px), or 4K (4096px) resolution tiers

Output sized for the destination platform on the same call

Adapt one shoot across every channel

One product photo becomes a square Instagram post, a 16:9 display banner, a 9:16 Story, and a 4:3 catalog hero. Run the same source through Smart Resize with different aspect ratios and ship every platform format from a single asset.

One source image to every platform format

Square, widescreen, vertical, cinematic, all on one API

Consistent brand presentation across every surface

Built for production scale

Process thousands of images per job with different aspect ratios and resolutions per image. Designed for catalog adaptation, multi-format ad rollouts, content library normalization, and post-processing AI-generated outputs into delivery-ready sizes.

Batch processing with async webhook delivery

Different aspect ratios and resolutions per image in a single job

JPEG, PNG, and WebP input/output up to 4K on the long side

Smart resize for every content format

From multi-format ad campaigns to editorial layouts. One source, every platform.

Ad Agencies & Campaign Teams

Adapt one hero shot into every ad placement: square for Instagram feed, 16:9 for display, 9:16 for Stories, 21:9 for cinematic banners. Ship multi-format campaigns from a single source. Think: Meta Ads, Google Display, TikTok Ads.

Ecommerce Brands & DTC

Resize PDP imagery for hero banners, listing thumbnails, and lifestyle hero shots without reshooting. Keep one canonical product photo and derive every catalog size from it. Think: Shopify Plus, Amazon A+, BigCommerce.

Social Media & Creator Tools

Add aspect-ratio conversion to your creator product. Let users post once and publish everywhere: portrait for Stories, landscape for feed, square for profile. Think: Canva, Later, Buffer, Unfold.

Real Estate & Architecture

Reframe property and interior photography for listing hero shots, social posts, and brochure layouts. One photo set, every layout your team ships. Think: Zillow, Airbnb, Compass, Redfin.

Publishing & Editorial

Adapt editorial imagery to full-page spreads, hero banners, and any layout without cropping subjects out. One photoshoot, every page format. Think: magazines, content sites, brand editorial teams.

AI Image Platforms

Post-process AI-generated outputs into delivery-ready aspect ratios. Headshot platforms, avatar tools, and ad-generation products turn one generation into every format their users care about. Think: BetterPic, HeadshotPro, Magic Brief.

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Working with Runflow changed how we build. Our developers can integrate a new AI feature by calling an endpoint, they don’t need machine learning expertise, infrastructure knowledge, or DevOps skills. We just focus on making the best product, and Runflow handles everything underneath.

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CEO, BetterPic

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Frequently asked questions

One source image. Every aspect ratio your channels need.

One API call. $0.55/image. Convert any source to any aspect ratio at 1K, 2K, or 4K. Start with $10 in free GPU credits on signup.

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