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Compressore di immagini

Comprimi immagini JPG, PNG e WebP nel browser senza caricarle online.

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Per ora la guida dettagliata di questo strumento (come si usa, esempi e domande frequenti) è disponibile in inglese.

What this tool does

The Image Compressor re-encodes a JPG, PNG, or WebP in your browser. Set a quality from 10 to 100, pick an output format, and compare the file size the page reports after you press Compress. Use it before you attach a photo to an email or a page. PNG output is lossless in this tool, so a flat graphic may barely shrink. Compressing a JPEG again can add artifacts.

How to use

  1. Choose a JPG, PNG, or WebP, or drag it onto the box. The limit is 25 MB, and neither side can exceed 8,192 pixels.
  2. Set quality from 10 to 100. The control starts at 80. Quality changes JPEG and WebP. It does not change PNG encoding on this page.
  3. Choose JPG, PNG, or WebP as the output, then press Compress.
  4. Read the original size and the new size on the page, then download the result. Reset clears the image from this tab.

Examples

  • A photo saved as JPEG at quality 80

    Open a camera JPEG and leave quality at 80, which is the starting value. Choose JPG and press Compress. The browser draws the picture and encodes JPEG at 0.80. The page then shows the original file size and the new file size for that image. Those two numbers come from your file. This explanation does not publish a sample size, because a different photo produces a different result.

  • A screenshot that should stay PNG

    A screenshot is often a PNG of flat color and sharp text. Re-encoding it as PNG on this page is lossless, and the quality slider does not change that encoding, so the file may not get smaller. Converting that same screenshot to JPEG at quality 80 throws away detail. Text edges and flat areas can pick up blocks. If you need the letters to stay crisp, keep PNG, or resize the image first on the Image Resizer.

  • A file the page will not open

    GIF, HEIC, and SVG are rejected. A file over 25 MB is rejected so the tab stays responsive. A side longer than 8,192 pixels is rejected. Quality below 10 or above 100 is rejected. Convert those files to JPG, PNG, or WebP in another tool first, or export a smaller image.

How it works

Compression runs in the browser with the canvas. The image is drawn, then encoded to the format you chose. JPEG and WebP receive a quality value from 0.10 to 1.00, which is the slider divided by 100. PNG is encoded without that quality argument, so the slider does not make a lossy PNG. JPEG and WebP output are filled on a white background first, which matters for a PNG that had transparency.

Quality is not a file-size dial for every format

Lower quality usually makes a smaller JPEG or WebP, and it also removes more detail. Quality 80 is a reasonable start for a photo. Step down toward 70 or 60 only after you look at the preview. Quality 10 is the lowest the page allows, and it is visibly harsh on most photos.

PNG on this page does not use the slider. A logo or a UI screenshot can stay large after a PNG re-encode. That is expected. This is not a palette reducer such as a specialized PNG optimizer. If size matters more than sharp text, switch the output to JPEG or WebP and accept the loss.

What each format throws away

JPEG is lossy. Repeating JPEG compression on an already compressed photo adds artifacts, even at a high quality. WebP at the same slider setting is also lossy here. Neither format keeps a transparent background on this page, because the canvas is filled white before those encodings.

PNG output is lossless relative to the pixels drawn on the canvas. It still will not recover detail a JPEG already lost. Starting from a JPEG and saving PNG makes a larger file of the same soft picture. It does not restore the original camera file.

Resize before you chase a tiny file

A 4000 pixel photo stays 4000 pixels after compression. The byte count falls because the encoding is harsher, not because the pixel dimensions changed. If the picture will be shown at 1200 pixels, resize it first, then compress. The Image Resizer on this site changes width and height. This page does not.

After Compress, use the sizes the page prints for your file. A before-and-after from someone else’s photo is not a prediction of yours.

Privacy

The file is read and re-encoded in this tab. It is not sent to Tools Star Hub. Reset and leaving the page drop the preview. Analytics, if you accept it, does not receive the image.

Tips

  • Start at quality 80 for a JPEG photo, look at the preview, then lower the slider only if the file is still too large.
  • Keep screenshots and logos as PNG when the text must stay sharp. Do not force them to JPEG just to see a smaller number.
  • Expect a second JPEG pass to look worse than the first, even if the new file is smaller.
  • Check transparency. JPEG and WebP output on this page sit on white.

Limitations

GIF, HEIC, and SVG files are rejected. An image must be 25 MB or smaller, and neither side can exceed 8,192 pixels. Quality must be from 10 to 100. PNG is re-encoded without a lossy quality control, so a flat graphic may barely shrink. JPEG and WebP are lossy, and compressing a JPEG again can add artifacts. The page shows the resulting file size after you compress. It does not promise a target size in advance.

See the disclaimer for what these tools do not cover.

FAQ

How do I compress a JPEG?
Open the JPG, set quality between 10 and 100, choose JPG, and press Compress. The control starts at 80, which encodes at 0.80. The page shows the new file size for that image.
Why did my PNG barely shrink?
PNG output on this page is lossless, and the quality slider does not change that encoding. Flat screenshots and simple graphics may stay almost the same size. Choose JPEG or WebP if you can accept some loss of detail.
Should I turn a screenshot into a JPEG?
Only if a smaller file matters more than sharp text. JPEG at quality 80 can block around letters and flat colors. Keep PNG when the edges need to stay clean.
Which files are rejected?
GIF, HEIC, and SVG are not opened. Files over 25 MB are rejected, and so is any side longer than 8,192 pixels. Quality outside 10 to 100 is rejected.
Is my image uploaded?
No. The JPG, PNG, or WebP is re-encoded in this tab at the quality you set. The file is not sent to Tools Star Hub.
Does it work on mobile?
Yes. You can open this page on a phone or tablet. File pickers and downloads use the browser on your device. Large files may be slower on a small phone than on a desktop.

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