What does the Image Resizer and Center Cropper do?
Use this tool when you need a browser utility that renders an image at exact pixel dimensions with fit, crop, or stretch behavior. It accepts one JPEG, PNG, WebP, or browser-supported AVIF image and returns a locally generated JPEG or PNG at the requested size. Results are deterministic for the same input except where cryptographic randomness, current time, or a live provider response is part of the task.
Fit, crop, and stretch have different tradeoffs
Fit inside preserves all content and aspect ratio. Center crop fills the exact frame by removing edges. Stretch fills the frame without cropping but distorts the image when aspect ratios differ.
How do you use it?
- Choose one supported image, then enter the target width and height up to 12,000 pixels.
- Choose Fit inside, Center crop, or Stretch and decide whether to lock the source aspect ratio.
- Select Convert image, verify the reported dimensions and format, then download the result.
Worked example
Resize a 1600 × 900 PNG without cropping
Input
Source: 1600 × 900 PNG
Width: 800 px
Fit: Fit inside
Lock source aspect ratio: onOutput
Dimensions: 800 × 450 px
Format: image/pngLocking the 16:9 aspect ratio updates the height to 450 pixels when the width becomes 800.
Common errors and fixes
| Symptom | Likely cause | Fix |
|---|---|---|
| The image has empty space inside the requested canvas. | Fit inside preserves the entire source and centers it within the target dimensions. | Choose Center crop when filling every output pixel is more important than preserving the full frame. |
| An enlarged image looks soft or pixelated. | Upscaling interpolates existing pixels and cannot recover missing detail. | Start from a larger source or keep the target dimensions at or below the original size. |
Important behavior of Image Resizer
Upscaling creates more pixels but cannot restore missing detail.
Standards and implementation references
- MDN — CanvasRenderingContext2D.drawImage() (opens in a new tab)Documents the browser drawing API used for scaling and positioning.
- WHATWG HTML — Canvas (opens in a new tab)Defines canvas image rendering and export behavior.
Frequently asked questions about Image Resizer
Does the Image Resizer upload my input?
No. Processing runs in the current browser tab, and the page does not send tool input to a KitLumi processing endpoint.
What input does the Image Resizer accept?
It accepts one JPEG, PNG, WebP, or browser-supported AVIF image. The workspace checks the input and reports malformed or unsupported values before it produces a result.
What does the Image Resizer produce?
It produces a locally generated JPEG or PNG at the requested size. Copy and download controls appear when the output format supports them.
What limitation should I know?
Upscaling creates more pixels but cannot restore missing detail.
What changed?
Added Exact pixel resize, Aspect lock, Center crop, Local canvas export, responsive controls, explicit runtime disclosure, and tested browser output.