FIRST CH TOOLS LOCAL PROCESSING — your images never leave this device 日本語

FIRST CH TOOLS / 34 IMAGE RESIZER

Image Resizer & Cropper

Set image dimensions in pixels or by aspect ratio. Give just the long edge, crop to a ratio from the centre, or process a whole batch at once. Everything happens inside your own browser.

Drag & drop images here or click to choose files (PNG / JPEG / WebP, multiple allowed)

PNG is lossless, so the quality slider does not apply. JPEG cannot hold transparency, so padding is filled with white (or the colour you pick).

How to Use

  1. Choose how to sizeLong edge, width, height or percentage — or give width × height to crop to a ratio.
  2. Add imagesDrag & drop PNG/JPEG/WebP files, or click to choose them. Processing starts right away.
  3. SaveSave one at a time, or take them all in a single ZIP. Change any setting and everything is redone automatically.

About This Tool

Photos for a website, a social header, a figure for a document — each use has a size it wants. This tool takes one instruction such as "long edge 1200px" and applies it to a whole batch, and it also crops to a ratio such as 16:9. Cropping is measured from the centre; choose "fit the whole image" instead and padding (transparent or a colour) is added so the result matches the frame exactly.

The work is done by the browser's Canvas, so no image is uploaded anywhere. Downscaling happens in halving steps, which keeps edges from going ragged even when an image shrinks a long way in one go. WebP output alone goes through the same libwebp (WebAssembly) used by the WebP converter, to avoid differences between browsers. Images are never enlarged past their original size unless you ask — enlarging cannot bring detail back.

Settings can also arrive as URL parameters (you still pick the files yourself). For example /en/resize/?mode=long&size=1200&format=image/webp&q=80, or for a ratio crop /en/resize/?mode=box&ratio=16:9&w=1600.

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