why do some pictures online load top to bottom (line of pixels line by line) and other go from blurry to clear?
In: Technology
You and your eccentric friend are coloring two copies of a picture. You are picking up a green crayon and coloring all of the green things. Then grabbing a blue crayon and coloring all of the blue things, etc. Your friend is starting at the top and coloring each object he comes to as he works his way down. He colors the sky blue and then the leaves of the trees green. Then he colors the pond blue, the ducks yellow, and then the turtle green.
Your picture is like the blurry image that gets better. Your friend’s is the image that goes pine by line.
The top comment answered what I was gonna say but a note is that most photo types are bit maps with arrays of indices between 0-255 standard and when they go from blurry to clear that index is being changed to render, 255 being filtered and 0 being clear.
Top to bottom is how an image loads when it loads normally. Blurry to clear means the website is loading a lower quality version of the same image first then a higher quality one when its needed.
People have mentioned about it being two different strategies of saving image data. From what I understand earlier it used to be line by line with the blurry to clear was developed later but still in the early years of internet.
I think it was done so that on slower connections where data is coming slowly or unreliable connections where the connection can break after partial data, you still get the full view of the image even if it’s low res compared to getting top X% lines of the image but it still being useless.
Also from a web design perspective, as soon as the first blurry version comes in the sizing box of the image is decided and filled. So your page feels filled and the grids etc align. In lined version you would have empty spaces in your page everywhere until everything is fully loaded.
As others have said it is just two ways of storing and loading an image. To give ELI5 examples:
Line by line is like putting together a puzzle the plus there is that when the image is done, it’s full quality. But with slow speed, it can take longer to understand what the image is.
Going from blurry to clear is like painting the picture. You start with the general colours and add details as you go. The plus there is that you can often understand what the image is before it is fully completed. But with slow speed it may take longer to get all the details to show.
You could also be seeing [https://blurha.sh/](https://blurha.sh/) which just first displays a tiny approximate representation of the original and once that loads, it seamlessly replaces the blurry picture.
I haven’t experienced this since 90s and early 2000s. Internet is so much better now, images just appear. I wonder if <256k connections still exist
I’ve never heard of images going blurry to clear, but from all the replies it seems common. Weird
just saying, if you’re uploading a webcomic, DON’T use the format that loads blurry… it just hurts the eyes whenever one clicks a new page and tries to read it.
And then I have to wait for the whole image to load instead of starting from the top, because a blurry image is useless when you can’t make out the text.
How are you seeing images load in these days?
I haven’t experienced that since AOL dialup era.
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