What is the WebP format?

1What is the WebP format?

WebP is an image format that Google introduced in 2010 with a clear goal: to make web pages load faster by using smaller images. In a single format it brings together what used to take three: it can compress with loss like JPG, without loss like PNG, and store animations like GIF, in addition to supporting transparency.

Today it is used by websites, online stores and apps for the bandwidth it saves. When you save an image from a browser and get a .webp file instead of a .jpg, it is because the site was serving it in that format.

2How does WebP compression work?

In its lossy mode, WebP uses the prediction techniques of the VP8 video codec: it predicts each block of the image from neighboring blocks and stores only the difference, which compresses efficiently. This lets it reach a smaller size than JPG with comparable visual quality. In its lossless mode, it uses other strategies, such as reusing pixels already seen and local color palettes, which generally make it more compact than PNG.

A distinctive advantage is that lossy mode also supports transparency, something JPG can't do and PNG offers only at the cost of a lot of weight. This makes it practical for product images with cut-out backgrounds.

3Advantages and limitations of WebP

Advantages: lighter files, transparency, animation, and a single format for almost everything. Limitations: compatibility isn't as universal as JPG's; editors, office programs or older systems may not open it, and some official portals accept only JPG, PNG or PDF. It also has a maximum size limit of 16,383 pixels per side, which is rarely reached.

There is also the workflow factor: if you download a WebP image to upload it to another site and it rejects it, you will have to convert it. Modern browsers support it without problems, but outside them it's worth checking.

4WebP vs. JPG, PNG and GIF

Compared with JPG, WebP usually gives smaller files at the same perceived quality, so it is a good choice for the web. Compared with PNG, it offers a lighter lossless mode and transparency with controlled loss. Compared with GIF, an animated WebP normally weighs far less and has more colors.

When not to use it: if the recipient needs to open it in old programs, if you are going to print it at a service that asks for JPG or TIFF, or if you will upload it to a form with a list of allowed formats. In those cases, convert to JPG or PNG depending on what you need to keep.

5Common problems with WebP files

The most frequent is that a downloaded image can't be opened, attached or uploaded because the destination doesn't recognize the format. The fix is to convert it to JPG if it is a photo or to PNG if it has transparency or text. Another case is wanting to put several WebP images into a document: “Images to PDF” lets you gather them into a PDF, which does open anywhere.

If you want to reduce the file size even more, “Resize image” and “Compress image” work on the pixels and the quality. Keep in mind that recompressing a lossy image again and again degrades its appearance, so it's best to start from the original.

6Practical tips for using WebP

For your website, serve WebP with a JPG or PNG fallback for very old browsers, and set the quality between 75 and 85 as a starting point. For product photos with a transparent background, lossy WebP usually beats PNG on file size. To archive originals, always keep the master file in a lossless format or the original JPG from the camera.

If you work with Rayo PDF GO, image conversions and compressions happen on your device, so you don't upload your files to outside services.

If your goal is just to cut file size for a website, try resizing first: an image 1,200 pixels wide works for most designs, and going from 4,000 to 1,200 saves far more than any quality tweak. Then adjust the quality until you can't see a difference.

7How to get the most out of WebP in Rayo PDF GO

If you downloaded a WebP image and need to use it in a document, “Images to PDF” includes it in a PDF that anyone can open. To adjust its size or dimensions, use “Compress image” and “Resize image,” and to remove extra borders, “Crop image.”

If what you need is to export pages from a PDF to use on a website, “PDF to images” generates images that you can optimize afterward. Always remember which format the destination requires: if you aren't sure, JPG for photos and PNG for graphics are the most compatible bets.