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Loading picture6/13/2023 ![]() We now face the following three challenges: Therefore, only the video data around the time requested by the user is requested by the server, so that the user can watch the video as fast as possible. If a user jumps to the end of a video, it would not be very efficient to load the complete video before the user can finally see the desired part. This feature, supported by each of the larger servers (Apache, IIS, nginx), is mainly used for video playback. Using HTTP range requests, a client can inform the server in an HTTP request header which bytes of the requested file are to be contained in the HTTP response. With Ajax, however, this is possible, provided that the server delivering the image supports HTTP Range Requests. Unfortunately, you can’t tell an img tag in an attribute how much of the image should be loaded at what time. Loading a progressive JPEG with two requests ( Large preview) when all preview images in the current viewport have been loaded), the rest of the image should be loaded without requesting the part already requested for the preview again. The idea presented here is now to load only so many bytes of a progressive JPEG from the server that you can quickly get an impression of the image content. In the worst case, the browser will load an image completely before it starts loading the next one. Progressive JPEGs alone are therefore not the solution to give the user the fastest possible impression of the page. This is because modern browsers only allow six simultaneous connections to a domain. If your website consists of many JPEGs, you will notice that even progressive JPEGs load one after the other. For files larger than 10 kB, there is a 94 percent probability of a smaller image when using progressive mode according to Stoyan Stefanov of the Yahoo development team. In addition to the better user experience provided by the appearance that is displayed more quickly, progressive JPEGs are usually also smaller than their baseline-encoded counterparts. Baseline mode ( Large preview) Progressive mode ( Large preview) Instead of having the image built up from top to bottom during loading (baseline mode), a blurred image can be displayed very quickly, which gradually becomes sharper and sharper (progressive mode). JPEG files, for which lazy loading is mostly used, have the possibility, according to the specification, to store the data contained in them in such a way that first the coarse and then the detailed image contents are displayed. What if you could present a preview image to the website visitor without having to load additional data? This will be displayed blurred and later replaced by the original image. What both have in common is that you first generate a low-quality preview image. Low Quality Image Preview (LQIP) and the SVG-based variant SQIP are the two predominant techniques for lazy image loading. The Embedded Image Preview (EIP) technique introduced in this article allows us to load preview images during lazy loading using progressive JPEGs, Ajax and HTTP range requests without having to transfer additional data.
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