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Compresseur d'image

Outils d'image · Outil en ligne gratuit

Compresser les images JPEG/WebP avec un curseur de qualité.

Équipe CoderNewbieDernière mise à jour : 2026-09-20

Upload ImageClick to select an image

Output Format

Quality0.70

Original0 B

No image yet

Compressed

0 B

Compressed result will appear here

Comment utiliser Compresseur d'image

1Upload your image file or drag and drop it into the tool.
2Adjust the tool-specific settings (quality, size, format, etc.).
3Click the process button to apply changes.
4Download the processed image.

Fonctionnalités

✓100% gratuit — sans inscription, sans abonnement, sans publicité
✓Fonctionne entièrement dans votre navigateur — vos données ne quittent jamais votre appareil
✓Rapide et léger — résultats instantanés
✓Multiplateforme — compatible ordinateur, tablette et mobile

Qu'est-ce que Compresseur d'image ?

Image compression reduces image file size while maintaining acceptable visual quality. Lossy compression (JPEG, WebP) discards data permanently; lossless compression (PNG) preserves all data. Modern web performance requires optimized images — uncompressed images are the #1 cause of slow page loads.

Comment fonctionne Compresseur d'image ?

JPEG uses Discrete Cosine Transform (DCT) to discard high-frequency visual data. WebP uses VP8 intra-frame encoding with better compression. The browser's Canvas API decodes the image, re-encodes it at a chosen quality level (0-1), and outputs a compressed Blob. Higher quality = larger file; lower quality = artifacts.

Cas d'usage courants

✓Web performance — reduce LCP (Largest Contentful Paint) time
✓E-commerce — faster product image loading increases conversions
✓Email attachments — fit images within size limits
✓Storage savings — reduce cloud storage costs for user uploads

JPEG vs WebP vs PNG

JPEG: lossy, best for photos, no transparency. WebP: lossy or lossless, smaller than JPEG, supports transparency, 97% browser support. PNG: lossless, supports transparency, larger files, best for graphics/screenshots. For web photos use WebP with JPEG fallback; for graphics use PNG or SVG.

Sécurité et confidentialité

This tool processes images entirely in your browser using the Canvas API — your images are NEVER uploaded to any server. This is critical for sensitive images (medical, legal, personal). Server-based compressors see your images; browser-based ones cannot.

Détails techniques

JPEG: DCT-based, quality 1-100, no alpha channel, baseline/progressive. WebP: VP8-based, 25-35% smaller than JPEG at equivalent quality, supports alpha. PNG: DEFLATE compression, lossless, supports 8/16-bit per channel. Canvas API: toBlob() with quality parameter for JPEG/WebP. EXIF metadata is stripped during re-encoding.

Questions fréquentes

What quality level should I use?

For web photos: 75-85 (good balance). For thumbnails: 60-70. For high-quality displays: 90-95. Below 50 shows visible artifacts. WebP at 80 usually matches JPEG at 90 with smaller size.

Does compression affect image dimensions?

No. Compression reduces file size, not pixel dimensions. To resize, use a separate image resize tool. Compression only changes quality and encoding efficiency.

Is my image uploaded to a server?

No. This tool uses the browser's Canvas API — all processing happens locally. Your images never leave your device. This is safer than server-based compressors.