Top-to-bottom seems to be the standard direction for an image to load. Why is it so ?

It took me 10 seconds for every image to load while reading leisuretown comics on a slow connection. I wondered why those couldn't load from left-to-right, naturally following the reading direction..? I wouldn't have to wait for the entire strip (and its end) to load to be able to read it...

Being read right-to-left is also an option (for mangas, or arabic comics if any)

And I guess some might use the bottom- to-top setting for kinky purposes.

So here's what I propose : While you compress and save your picture, you may choose the direction in which it'll load. Default is top-bottom. It's that simple.

Sorry if it's already proposed, I couldn't find anything in the archive, and google didn't help me much.
-- shitwolk, Jul 20 2008

Top left http://s122.photobu...?mediafilter=images
Different file sizes - why? [nineteenthly, Jul 20 2008]

Interlaced .gif http://webstyleguid.../graphics/gifs.html
fuzzy to sharp instead of top>bottom [csea, Jul 22 2008]

interlacing and progressive display http://www.vias.org...e/chapter08_07.html
Mentions a little about progressive display on JPEG [Bad Jim, Jul 22 2008]

Hello, are you new? If so, welcome.

Anyway, yes, i see where you're coming from. I seem to remember that bitmaps load from the bottom, maybe because they're arrays.

It has occurred to me that a JPEG rotated through ninety degrees, which must never be done of course because it loses data, is sometimes a different size. If it were compressed after rotation, presumably less data would be lost. Then again, the digital photos i've used via scanners, 'phones and rather crappy cameras already seem to be JPEGs when they get to the PC, which offends my sense of control.

Yes, good [+].
-- nineteenthly, Jul 20 2008


[admin: I renamed the idea to put spaces into the title - if it's all one long word, the page gets laid out to squeeze the comments way over to the side on a small browser window.]
-- jutta, Jul 20 2008


//It has occurred to me that a JPEG rotated through ninety degrees, which must never be done of course because it loses data//
Nope, shouldn't.
-- AbsintheWithoutLeave, Jul 20 2008


I was given to understand that the JPEG compression process involved dividing the image into 8x8 pixel blocks, and applying transformations to those, so that if it's rotated, the blocks are likely to overlap and applying the same transformations again will lose data. Is that wrong then?
-- nineteenthly, Jul 20 2008


There shouldn't be any need to apply the discrete cosine transform (lossless), quantisation (lossy) and Huffman coding (lossless) again, assuming an exact 90/180/270 degree rotation.
Some software *may* do this, but that would be silly software.
A simple orthogonal rotation should not incur any further data loss.
-- AbsintheWithoutLeave, Jul 20 2008


OK, rotating and resaving using the Gimp on my Photobucket photo:

Just saving four times without transforming makes it nine bytes bigger. Rotating ninety degrees and saving four times makes it four hundred and fifty-one bytes bigger. There is some kind of difference there. What is it?
-- nineteenthly, Jul 20 2008


//There is some kind of difference there. What is it?//
Excess EXIF?
-- AbsintheWithoutLeave, Jul 20 2008


Welcome to HB
-- Voice, Jul 21 2008


The 3D program Blender offers the ability to render an image starting at the center and working spiral outward from there, given that the focus of the image is typically and more frequently near the center than the top left.
-- napoleonbag, Jul 22 2008


I want it to load from the navel - I mean middle - outward
-- nomocrow, Jul 22 2008


In the early days of the WWW, many images were in .GIF format (by Compuserve?,) and because of the relatively slow dialup modem connections (33kbps was blazing fast at one point) the favored format showed a low-resolution image that was gradually sharpened. [link]
-- csea, Jul 22 2008


//naturally following the reading direction//
Is it only a single line of text across the image? If so, they could put that into plain HTML text above or below the image, so you could read it while it's loading.

If it takes a long time to load, the site was not designed for slow connections. So the webmaster wouldn’t bother with a loading direction.

A code for special effects would be interesting – various wipes, zooms, scrolling, etc. But on a slow connection, adding more code makes it slower.
-- Amos Kito, Jul 22 2008


[csea], though this connection is far faster nowadays, that's still pretty fast compared to the three hundred baud i know.
-- nineteenthly, Jul 22 2008


It seems JPEG supports progressive display. My copy of Paint Shop Pro has a progressive option in the Save dialog. According to the source I've linked to, the quality of early passes is pretty good too.

If Leisuretown Comics simply saved their JPEGs as progressive, you would be able to read the whole thing before the image was even half downloaded. Real solution: Send them an angry email.
-- Bad Jim, Jul 22 2008


It is possible to rotate JPEG images by multiples of 90 degrees without any loss of picture quality or change in file size. The transformation must be done on raw JPEG data, by a program designed for the purpose. Converting a JPEG image to a bitmap, rotating it, and then converting back to JPEG, will nearly always result in a loss of quality, increase in file size, or both.
-- supercat, Jul 23 2008


thanks all for the feedback, the welcomes, and the welcome title correction!

First of all, I think that the debate about JPG lossless transform capabilities may be out of place; it may even be about something else than compression : It is about the sequence in which the image parts (lines, blocks) will be unpacked (and a metadata hint of several bytes)..

I know about the progressive display of JPGs and the interlaced GIFs, but these don't fulfill my wish of getting the sharp, definitive image, starting from its most urgent part.

In that manner, what napoleonbag says about the Blender approach is ++ ! Starting from the center, in a way or another, may exactly be the point for some images.

For those who don't know, the Leisuretown comics were all made between 1997 and 2000 ; these were 56k/ISDN times. They were bandwidth- conscious JPGs around 80kb each. Progressive JPG wouldn't have made them readable, and would have added some unnecessary bytes.

The only sadness (and it's the case for ALL web comics!) is the vertical loading delay... I can't even believe this issue hasn't been approached since then.
-- shitwolk, Jul 23 2008


There is a fairly simple workaround for webcomics using Javascript. You can use the "onload" event in an image tag to load the picture for a different image tag. You can set up a chain where loading one image starts another loading, loading that one starts another etc. If your comic is composed of several smaller images held together in a table, this means you can load the images in the order of your choice.
-- Bad Jim, Jul 23 2008


Surely, if the text arrived first you'd be in danger of spoiling it? Also, i seem to remember that some image files are or were compressed with the order of the data zig-zagging across the picture. I'm probably talking bollocks again.
-- nineteenthly, Jul 24 2008


That's just bloody excellent!
-- nineteenthly, Jul 24 2008



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