Preyfar said:
Some theory behind the math as to why, at this time, we really don't want to allow uber-huge images on FA:
Image at 248K downloaded 550 times = 134.4MB
Image at 2.6MB high res downloaded 550 times = 1.43GB
I like number theory stuff like this, so I'll do a bit of my own. I took a 1320x1600 picture by Fel, saved it at 100, 90, 80, 70, 60, and 50% zooms with 95% quality JPEGs each time. The results are as follows
At 100% zoom it is 100% the image size and 100% the file size.
At 90% zoom it is 81% the image size and 86% the file size.
At 80% zoom it is 64% the image size and 72% the file size.
At 70% zoom it is 49% the image size and 60% the file size.
At 60% zoom it is 36% the image size and 48% the file size.
At 50% zoom it is 25% the image size and 38% the file size.
What does this mean? When you start with a higher resolution image and you shrink it down, its file size shrinks slower than the number of pixels it occupies. So looking at the 50% zoom image which is 4 times smaller on screen, the file has only shrunk by a factor of 2.63.
Why should we care? Well, it means that if you're going for the best "bang for your buck" so to say, the larger the image is, the more pixels you get per KB. So while it's obviously a silly thing to increase a picture's resolution after making it, if you start higher, the larger picture will probably be more "size efficient" than the smaller one.
Why does
that matter? It means if you choose to upload a picture at two resolutions, one twice the size of the other, its file size will probably be well under what you'd expect--four times the size compared to the original.
This makes sense if you think about it, the intensity and number of transitions is usually smaller than if you were to simply tile the image four times.
SO! That's good news, the amount of detail we get goes up faster than the file size. The other good news is that we're not usually looking at such dramatic examples as the 248 KB vs 2.6 MB (don't know where you got those, but anyway!). If somebody chose to put an image up at 1600x1200 rather than 800x600, it'd only go up by a factor of (assuming it's similar to the Fel picture) 2.6 or so, rather than 10+. So if the original picture was 248 KB, the full view one would be 645 KB.
But, you say, increasing the site's bandwidth use by a factor of 2.6... that's a lot, that might overload the site and cause me to pay a bunch more!
Well, the
extra good news is that, obviously, not everyone is going to upload at higher resolutions. Plenty of artists put out these little images which are 500 pixels on a side or perhaps 800. In order to make something twice as big, they'd either have to scan at twice the resolution (doable I guess), work at twice the resolution (a lot more work) or put up something which is already huge (a photo or an OC session screenshot). People typically don't push the 1280 pixel limit right now anyway, so the impact would probably be pretty minimal.
I do like what you had talked about, with the smaller image by default to save bandwidth, and the option to view the larger image on demand for those who care. That's kinda what I'd been recommending a number of posts back.
As I said before though, maybe I'm just being too forward looking. If you increase the size limit gradually, say kick it up to 1600 pixels width in 12-18 months, then higher after that, it would probably minimize the number of problems, and naturally increase as users wanted to work on larger canvases and had more screen space to view images too. Then again, if you just turned the limit up now, the fact that most people don't push the limit as is means it'd have little impact in bandwidth usage. If you're afraid of users who don't know what they're doing uploading full 5 megapixel photos, you could have a checkbox for "downsize to 1280 pixels" checked by default, which would let the knowledgable users take the time to ask for a larger image.
Yeah, I'll stop talking now.