Exploring Hidden JPEG Features

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The lossy compression algorithm used by JPEG was useful for those on the early Internet not only because it enabled pictures to be shared easier, but because it allows a low-resolution version of the image to load first. This meant that users could make out the gist of an image before it finished downloading. This was a great feature for those on slow connections, but it hides some other capabilities of this image format as well.Rather than effectively splitting up the image into chunks, each with successive amounts of detail, [maurycyz]’s project shows that this can be exploited to load more than one picture. The first is loaded into this lower-resolution area, with a second unrelated picture showing up once the higher-resolution information is available. Essentially this makes a one-way .gif of sorts. Though this method is only capable of loading about nine frames, which is not enough for much animation. Further limiting things is that there’s no way to encode timing data, so on fast computers with fast connections the animation could load faster than a user could see.Still, it’s an interesting quirk of this older image standard, one which still is in widespread use today. And it’s also true that it’s hard to say in what ways various technologies will be used in the future. JPEG images have also been the subject of some artistic projects that might not have been possible without the JPEG standard itself, and even as other formats have tried to supplant it, it still maintains its firm grip on the images on the Internet. More JPEG, please!