Compressor de imagens

What "cropping" really does to your image

Cropping is the act of discarding the parts of an image outside a chosen rectangle and keeping only what is inside it. It is not resizing — the pixels that survive keep their original resolution; you simply throw away the rest. This tool performs that operation entirely on an HTML canvas in your browser. When you select a file it is read with a FileReader into a data URL and drawn locally, so the image is never uploaded to a server. You can confirm this by disconnecting from the network: the cropper still works because all the pixel math happens on your own device.

The eight handles and what each one does

The crop rectangle has eight draggable handles: four at the corners and four at the edge midpoints. The corners (nw, ne, sw, se) resize two sides at once, letting you reshape the box diagonally. The midpoint handles (n, s, e, w) move only a single edge, so you can trim one side without disturbing the opposite one. Dragging inside the rectangle moves the whole selection, and dragging on empty canvas starts a brand-new rectangle from scratch. A faint rule-of-thirds grid is drawn over the selection — aligning a horizon or a subject's eyes to one of those lines is a classic composition trick that often improves a photo.

Aspect ratios: free versus locked

By default the crop is Free, meaning width and height move independently. Choosing a preset — 1:1 (square, for profile pictures and Instagram), 4:3 or 3:2 (classic photo prints), 16:9 (video and widescreen thumbnails), or 9:16 (vertical stories and Reels) — locks the ratio so the height is always recomputed from the width as you drag. You can also type a custom W : H pair. When a ratio is locked, resizing one dimension forces the other to match, which guarantees the export fits its destination frame without letterboxing.

A worked example

Say you upload a 4000 × 3000 photo and want a square avatar. Click 1:1, drag the selection over the face, and watch the readout — it shows the crop in original image pixels, not screen pixels, because the canvas displays a scaled-down preview. If it reads Crop: 1200 × 1200 px, your downloaded file will be exactly 1200 × 1200, regardless of the zoom level you used while positioning. Set the format to JPEG, nudge quality to about 85%, and click Download. The tool re-renders the source image to a clean off-screen canvas (without the dark overlay or handles), extracts just the crop region, and saves it.

Zoom, rotate, and flip

• Zoom (50–200%): this scales the on-screen preview so you can position the crop precisely on a large image. It does not add detail — zooming past 100% magnifies existing pixels.
• Rotate 90°: the clockwise and counter-clockwise buttons turn the image in quarter turns, swapping width and height. Use this to fix a photo shot in the wrong orientation.
• Flip H / Flip V: mirror the image horizontally or vertically. Handy for correcting selfies that look "backwards" or for design symmetry.

PNG versus JPEG, and the quality slider

The format choice matters more than people expect. PNG is lossless and supports transparency — pick it for logos, screenshots, diagrams, and anything with sharp text or flat color. JPEG is lossy but far smaller for photographs, and it exposes a quality slider (50–100%, defaulting to 85%). A setting of 80–90% is the sweet spot: visually indistinguishable from the original for most photos while cutting the file to a fraction of the PNG size. The quality control only appears for JPEG, because PNG compression is lossless and has no quality trade-off to expose.

Common mistakes to avoid

• Saving photos as PNG. A photographic crop stored as PNG can be several times larger than the equivalent JPEG with no visible benefit. Reserve PNG for graphics and transparency.
• Expecting zoom to add resolution. The pixel dimensions of your export come from the crop region in the original image, not from how far you zoomed the preview. Crop a small area and you get a small file.
• Cropping then re-saving repeatedly as JPEG. Each JPEG save re-compresses and degrades the image. Crop from the original whenever possible rather than from an already-compressed copy.
• Ignoring the aspect lock for platform uploads. If a site expects 16:9 and you upload a free-form crop, it will pad or crop your image unpredictably. Lock the ratio first so what you see is what gets published.