In a sense this is an unfair test, because a JPEG may contain artifacts due to compression that would not be present in the original raw image, and conversion to WebP may try to retain those artifacts. But we wanted to know what happens when we convert an image that was has already been compressed as a JPEG. Some studies compare WebP with JPEG by taking uncompressed images and compressing them to JPEG and WebP directly.The corpus consisted of 23,500 images (JPEG, PNG and GIFs). We evaluated WebP based on a collection of images gathered from the websites of our customers.But before we released our WebP support, we decided to do a survey based on the context on which we planned to use WebP: These studies provide a useful picture of how WebP performs. By the NumbersĪ few studies have been published of how well WebP compresses images compared with established formats. The “Content-Type” HTTP header tells the browser the true format of an image. For example, a JPEG image at that has been converted to WebP will still have that same URL. Note that WebP conversion does not change the URLs of images, even if the file extension in the URL implies a different format. These modes do not affect PNGs and GIFs, as these are lossless formats and so Polish will preserve images in those formats exactly. In lossy mode, the conversion sacrifices a little quality in order to shrink the image data further, but as before, there should not be a significant visible effect. In lossless mode, the conversion is done in a way that preserves the image as faithfully as possible (due to the nature of the conversion, the resulting WebP might not be exactly identical, but there are unlikely to be any visible differences). These modes are respected when JPEG images are converted to WebP. In lossy mode, Polish reduces the quality of JPEG images in a way that should not have a significant visible effect, but allows it to further reduce the size of the image data. In lossless mode, JPEG images are optimized to remove unnecessary data, but the image displayed is unchanged. Polish has two modes: lossless and lossy. Until the WebP ecosystem grows and matures, it is uncertain that attempting to optimize WebP is worthwhile.) If you put a WebP image on an origin site, Polish won't do anything with it. (Although Polish can now produce WebP images by converting them from other formats, it can't consume WebP images to optimize them. Google Chrome), so most websites using Polish should be able to benefit from WebP conversion. These WebP images are only returned to web browsers that indicate they support WebP (e.g. But it will also convert the image to WebP, if WebP can shrink the image data more than the original format. When this is enabled, Polish will optimize images just as it always has. Polish WebP conversionĬustomers on the Pro, Business, and Enterprise plans can enable the automatic creation of WebP images by checking the WebP box in the Polish settings for a zone (these are found on the “Speed” page of the dashboard): WebP images can be animated, so it can be used as a replacement for animated GIF images.Ĭurrently the main browser that supports WebP is Google’s Chrome (both on desktop and mobile devices).So it can be used instead of PNG, such as for images with sharp transitions that should be reproduced exactly (e.g. WebP can do lossless compression, and supports an alpha channel meaning images can have transparent regions.WebP can do lossy compression, so it can be used instead of JPEG for photographic and photo-like images.WebP is versatile and able to replace the three main raster image formats used on the web today: It is often able to compress the images into a significantly smaller amount of data than the older formats. It takes advantage of progress in image compression techniques since formats such as JPEG and PNG were designed. WebP is a newer image format for the web, proposed by Google. The main image formats used on the web haven’t changed much since the early days (apart from the SVG vector format, PNG was the last one to establish itself, almost two decades ago). But a new feature in Polish allows us to swap out an image for an equivalent image compressed using Google’s WebP format when the browser is capable of handling WebP and delivering that type of image would be quicker.ĬC-BY 2.0 image by John Stratford What is WebP? Up until now, Polish has not changed image types when optimizing (even if, for example, a PNG might sometimes have been smaller than the equivalent JPEG). It recompresses images and removes unnecessary data so that they are delivered to browsers more quickly. Cloudflare has an automatic image optimization feature called Polish, available to customers on paid plans.
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