uploaded jpeg quality comparo - where is the best

[samal]

before even I got interested in photography again in my life, I've been using fotki.com for my online storage and gallery website - basically I have every pic from my PC uploaded there as a backup and for viewing convenience.

it's a paid subscription that gives unlimited storage and I have about 20 G of pictures stored there, dated back to 2004

I see that most people here are using flickr, smug-smug as their web galleries of choice, and not too many use photobucket and such due to lower quality jpeg rendering engine, I guess.
So my question is, how a website can be rated or measured, besides creating an account on each website and uploading the same pic to compare?

if no other way to do it, here is what I would like to do and need your help with.

I will post here a few exposures that I uploaded to fotki.com, can someone please download them, upload to your website of choice and post here in this thread, so we can compare them?

Do you think it will be a valid test?

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[mrodgers]

....and not too many use photobucket and such due to lower quality jpeg rendering engine, I guess.

Nothing wrong with Photobucket. It's the people who upload huge image files that are useless to post in a forum anyways that have the problem. Use your head and Photobucket will look exactly as it does on your hard drive.

I see absolutely no difference at all....

FLICKR



Photobucket



Direct upload

[Garbz]

No not a valid test. Your images are littered with reds yellows and greens. A bit of basic knowledge about how JPEG compression works will give you an instant and very notable difference between the various sites.

Upload an image which is almost exclusively blue or as an alternative purple. As soon as a green channel is added to a picture the compression artefacts disappear almost completely. Case in point:

This is the exact same image just hue shifted, saved in the highest quality then uploaded on photobucket:



The site which compresses a purple picture the best will have the better quality compression. And this is something that is notable on a wider range of compression settings.

While the above is clearly visible it is not field relevant in most of the normal photos that people take. Also some people use flickr smug-smug as their gallery of choice because yahoo makes a free api available to access the flickr user account from other webpages, allowing people to autogenerate content on their own galleries like I do.