Why do some images initially load fast but look grainy, then fully load and “clear up”, while other images just take longer to load, but load in “full quality”?

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Why do some images initially load fast but look grainy, then fully load and “clear up”, while other images just take longer to load, but load in “full quality”?

In: Technology
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Different ways of sending it. Sometimes a website or program will load two images, one lower resolution and one higher resolution. The low res one is used to while the higher one sends, so you can get a feel of what you’re looking at.

This is good for say, stock image sites where you’re looking at a bunch of images and as you scroll through you won’t need to see everything and everything, especially as you scroll up to find the few images you want/need. It saves RAM so the site doesn’t stutter as you load more and more images, but also lets you know with relative ease the make up of the image itself.

Some image formats allow a low level resolution preview, others do not. This is why some come in grainy first on a slow connection. After it loads partially, you can see it.

Back in the dialup days, images loaded VERY slowly, so it was pretty desirable to start with a low resolution version of the image before filling in the details. It lets you decide whether or not you want to wait several minutes for the whole image before leaving the page.

The technique in general is called interlacing, and is a function of the image format. Nowadays it doesn’t really matter so much, as even a full screen image can load in a fraction of a second with good image quality.