Redimensionner une image en ligne

What Redimensionner une image does

Resizing changes the pixel dimensions of an image, its width and height. People resize images to meet size rules on websites and forms, to make photos lighter for email, or to prepare pictures for a specific screen or print size.

The tool redraws the image at the new size with high-quality smoothing. When shrinking by a large amount, it halves the image in several steps first, which avoids the jagged edges and patterns that one big step can cause. Enlarging is also possible, but it cannot add detail that the original does not have.

Comment utiliser Redimensionner une image

1. Déposez une ou plusieurs images dans la zone.
2. Réglez les options de l'outil Redimensionner une image et vérifiez l'aperçu.
3. Cliquez sur Appliquer. Chaque image est traitée dans votre navigateur.
4. Téléchargez les images modifiées.

When to use Redimensionner une image

• Meet the photo size rules of an online application, such as an ID or visa form that asks for exact pixel dimensions.
• Shrink camera photos to half their size before emailing them, so they send faster and fit inbox limits.
• Prepare product images at one consistent width for an online shop, so the product grid looks even.
• Scale down a large screenshot for a presentation or document without making the text jagged.

Settings explained

Resize by

Pixels lets you enter an exact width and height. Percentage scales the whole image by one value, which is quicker when you simply want it half or twice the size.

Width

The target width in pixels, from 1 to 10,000. The default is 1080. With Keep aspect ratio on, the height is calculated from this value.

Height (0 = auto)

The target height in pixels. Leave it at 0 to calculate it from the width. It is used when Keep aspect ratio is off, or when Width is set to 0.

Scale

Shown when resizing by percentage. It ranges from 1 to 400 percent, with 50 as the default. Values above 100 enlarge the image; for enlarging, the Image Enlarger also offers sharpening.

Keep aspect ratio

On by default, so the image keeps its proportions and is not stretched. Turn it off and enter both a width and a height to force an exact size; the image is then stretched to fit.

Output format

Same as input keeps the format, with HEIC saved as JPG and GIF or SVG saved as PNG. A Quality slider, with a default of 85, appears for JPG, WEBP and AVIF.

Format comparison

Qu'est-ce que le format PNG ?

PNG (Portable Network Graphics) est un format d'image créé par W3C en 1996. Il utilise une compression sans perte et gère la transparence. Les fichiers portent l'extension .png.

PNG was created in the mid-1990s as a free replacement for GIF, whose compression method was covered by patents at the time. It applies a filtering step and then compresses pixels with the DEFLATE algorithm, so every pixel is kept exactly. It supports full color, grayscale, palette images and a full alpha channel for smooth transparency.

PNG is the right choice for screenshots, logos, icons, diagrams, user interface graphics and any image with sharp edges, text or flat colors. It is also a safe format for images that need transparent backgrounds or will be edited again.

Because PNG is lossless, photos saved as PNG are often several times larger than the same photo saved as JPG or WebP. PNG has no lossy mode, and a standard PNG file cannot store animation.

PNG opens in every modern web browser, on Windows, macOS, Linux, Android and iOS, and in practically all image viewers, image editors, office suites and design tools. It is one of the most widely supported image formats.

Qu'est-ce que le format JPG ?

JPG (Joint Photographic Experts Group) est un format d'image créé par JPEG en 1992. Il utilise une compression avec perte et ne gère pas la transparence. Les fichiers portent l'extension .jpg ou .jpeg.

JPG, also written JPEG, is named after the Joint Photographic Experts Group, which wrote the standard. It splits an image into small blocks, transforms each block with a discrete cosine transform and discards the fine detail that the eye notices least. A quality setting controls how much detail is removed and therefore the file size.

JPG is the standard choice for photographs and other images with smooth color gradients, such as camera pictures, product photos and images for email or social media. It gives small files with good visual quality at moderate settings.

JPG does not support transparency or animation. Each time a JPG is edited and saved again, it loses a little more quality. Text, line art and sharp edges can show visible blocks or halos at low quality settings.

JPG is supported everywhere: in all web browsers, on all desktop and mobile operating systems, and on cameras, phones and printers. All image editors and office programs open it. It is the most compatible format for sharing photos.

Qu'est-ce que le format WEBP ?

WEBP (WebP) est un format d'image créé par Google en 2010. Il prend en charge la compression avec et sans perte, gère la transparence et peut contenir des animations. Les fichiers portent l'extension .webp.

WebP was developed by Google to make images on the web smaller. Its lossy mode is based on the VP8 video codec, and it also has a separate lossless mode. Both modes can include an alpha channel for transparency. The format also supports animation, so it can replace JPG, PNG and GIF in many cases.

WebP is a good choice for images on websites and in apps, where smaller files load faster. It works for photos, graphics with transparency and short animations, often at a smaller size than JPG, PNG or GIF.

Some older software, image editors, print services and upload forms still do not accept WebP. Lossy WebP always reduces color resolution, which can blur fine colored detail. At very high quality settings, the size benefit over JPG can be small.

All current major browsers display WebP, including Chrome, Edge, Firefox and Safari on recent versions of macOS and iOS. Windows, macOS, Android and most modern image editors open it, but some older desktop programs do not.

Qu'est-ce que le format AVIF ?

AVIF (AV1 Image File Format) est un format d'image créé par Alliance for Open Media en 2019. Il prend en charge la compression avec et sans perte, gère la transparence et peut contenir des animations. Les fichiers portent l'extension .avif.

AVIF stores images compressed with the AV1 video codec inside a HEIF-based container. It was developed by the Alliance for Open Media, a group that includes major browser and technology companies, as a royalty-free format. It supports high bit depth, wide color, HDR, transparency and image sequences.

AVIF is best for web images where file size matters most. It often produces smaller files than JPG or WebP at similar visual quality, especially for photos, and it is useful for HDR and wide color images.

Encoding AVIF is slow compared with JPG or WebP, especially at high quality settings. Many image editors, older devices and upload forms do not accept it yet. Fine detail and texture can look smoothed at low quality settings.

Current versions of Chrome, Edge, Firefox and Safari display AVIF. Recent Windows, macOS, iOS and Android versions can open it, sometimes with an extra codec extension, but support in editors, office software and older systems is incomplete.

Pourquoi utiliser l'outil Redimensionner une image de FansBond

La plupart des convertisseurs en ligne envoient vos fichiers sur leurs serveurs. L'outil Redimensionner une image de FansBond fait tout le travail dans votre navigateur, grâce à WebAssembly et aux API modernes des navigateurs. Vos fichiers restent sur votre appareil, ce qui est plus sûr pour vos photos privées, vos contrats et vos projets non publiés, et c'est souvent plus rapide puisqu'il n'y a rien à envoyer ni à télécharger.

Pas de file d'attente, pas de filigrane, pas de compte. Une fois la page chargée, l'outil continue de fonctionner même avec une connexion lente.

Tips for the best result

• To get an exact size without stretching, such as a square, resize so that one side fits, then trim the rest with the Crop Image tool.
• Images can have at most about 33 megapixels, for example 7680 × 4320 pixels, because larger images do not fit in browser memory.
• All images in a batch get the same size settings. With Keep aspect ratio on, each image still keeps its own proportions.
• Resizing works in pixels only. For printing, plan about 300 pixels for each inch of print size.

How Redimensionner une image works in your browser

When you add an image, the browser decodes it into raw pixels on your device. HEIC photos are decoded with a browser build of libheif, and AVIF with the libavif decoder. The pixels are then processed on an HTML canvas and encoded again in the format you picked.

JPG, PNG and WebP are encoded with your browser's built-in encoders, and AVIF with libavif compiled to WebAssembly. The compressors add MozJPEG for smaller JPG files and OxiPNG for lossless PNG optimization. Because everything runs locally, the speed depends on your device rather than on a server queue.

Privacy and security

Most online converters upload your files to a server, process them there and keep a copy for some time. Redimensionner une image works differently: the code is downloaded to your browser once, and your files are read and written only on your device.

You can check this yourself: after the page has loaded, turn off your internet connection and the tool still works. This makes it safe for contracts, IDs, medical records, private photos and unreleased work.