Image Resizer and Cropper は何をしますか？
Image Resizer and Cropper はブラウザ上でデータやファイルを変換するツールで、結果と制限を明確に示します。 検証済みの機能： Exact pixel resize, Aspect lock, Center crop, Local canvas export.
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.
使い方
- 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.
実際の入出力例
Resize a 1600 × 900 PNG without cropping
入力
Source: 1600 × 900 PNG
Width: 800 px
Fit: Fit inside
Lock source aspect ratio: on出力
Dimensions: 800 × 450 px
Format: image/pngLocking the 16:9 aspect ratio updates the height to 450 pixels when the width becomes 800.
一般的なエラーと対処
| 症状 | 原因 | 対処 |
|---|---|---|
| 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
このツール固有の制限： Upscaling creates more pixels but cannot restore missing detail.
標準と実装の参考資料
- 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.
Image Resizer — FAQ
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.
更新内容
実質的な更新： Image Resizer: Added Exact pixel resize, Aspect lock, Center crop, Local canvas export, responsive controls, explicit runtime disclosure, and task-specific examples and limitations.