A.net question

[RomNYC]

This may have been discussed before, so I apologize for repeating...

I notice a serious difference between the original photos that I upload on a.net and what I see once it has been uploaded, when I check my queue status. Are they only altering the pre-screened image in order to just give a preview and save some server space or is this what the screeners actually get to judge?

See for yourself:

Original


A.net's version

[Cary]

When the upload gets processed by A.net's server, it probably goes through a sever-side program like ImageMagick, and gets re-saved with the A.net banner/watermark at a certain JPEG quality. So it might get a little more JPEG artifacting, and there might be a color shift, if the original isn't saved as sRGB, and the post-IM image is. I think it's fair to assume that the original never gets saved (other than in some constantly-cleaned-out temp directory), and the screener always looks at the final processed image.

[mattdueck]

That must be the same for JP net as well. Just a thought.

[RomNYC]

Well, that blows then...

And Matt, my JP photos seem to be faithful to the originals...

[gonzalu]

Mat,

As for color shift, that can happen when you upload in AdobeRGB or some other color space other than sRGB. It looks like that may be what's happening above. I never saw this with my images on either DB. Cary is right, they are using likely a Unix PHP image library or similar to add the watermark and banner etc. They definitely strip all metadata :-(

Make sure your stuff is sRGB when you save. Also make sure you are CONVERTING TO profile, not just saving the profile.

[mattdueck]

Thanks everyone.

Matt

[RomNYC]

I'm reopening this question. I'm applying all of the sRGB profile stuff, and a.net still alters my images... I really don't get it. Anyone kind enough to give me step by step instructions?

[gonzalu]

Rom,

Can you send me an ORIGINAL RAW or JPG you are starting from, then a resulting image you're uploading to them? Please? I am very curious and would love to help from a technical standpoint. Please include a detailed list of steps you took from original to output jpg you are uploading... the more detail the better :-)

manny (at) manny (dot) org

Cheers!

[RomNYC]

Thanks Manny, check yer inbox

[gonzalu]

Thanks for the pics Rom... so for everyone's benefit...

Here is what I think may be going on. You may be editing from an 8 bit JPG with the color gamut stored in an sRGB space. This is OK as long as your image is not bordering on that space. Meaning if the colors are really close to any border of the gamut, a different editing program does NOT have to adhere tightly to that space. So, try to stay away from theedges of the space.

How you ask? By not moving data around too much. If you start with a 8 bit JPG, you should have as good of an exposure as possible and make sure your color balance is clsoe to spot on. Moving around the temperature only slides the data in the blue and red channels around, causing them to potentially fall outside the gamut for sRGB. If that happens, editing programs may not see the data and clip them. In your case I believe the red channel is getting slightly clipped by the processing engine at A.net.

You could do some testing yourself without using up slots on A.net and even attempting. Just do uploads, even with bad data in the fields and then just delete the entry after you get the resulting image processed with the logo etc.

Upload various versions from UNEDITED originals (resized of course) to heavily processed ones and see where they clip.

Also, do not change to AdobeRGB or ProFotoRGB during editing (if JPG originals) as that will just give your already low bit data a lot more room to move around in and potentially ending up where sRGB can't display it and have it clipped on output.

Use Save As.. engine and not the Save for Web engine which is much more discriminating in terms of making it tighter for the web.

[RomNYC]

This link fixed it for me:

http://www.viget.com/inspire/the-mys...b-color-shift/

[gonzalu]

OK great, so I was right, it had to do with the way the browser displays it... for you anyway. I do nto have these issues as I work in a controlled workflow beginning to end ... one of the benefits of RAW workflow. But, you probably never previewed your images in Internet Explorer before uploading.

Thanks for confirming what I felt was happening.

For everyone here, the exchange was over E-mail, not here ... I had told Rom that the images were not being properly displayed by Photoshop because he did not have Proofing on. Indeed when you turn on Soft Proofing, the images looks liek IE displays it and indeed the way it looks on screen when looking at it from A.net... it looks like his image is different only because he was not viewing his image in IE.

Photoshop can display your colors the way IE sees it, but you have to hit CTRL+Y to turn it on... it is off by default.

[RomNYC]

Yes, you were right. And the help most was most appreciated
Then I guess Firefox has that issue as well, since this is the browser that I use... However, when I preview my images in my browser, they look just like they do in PS. I also never had that issue when uploading to JP... Only at a.net did I have that problem.

Anyway, glad we found a fix for it :D

[gonzalu]

Yeah, Color Space and the aderence of it by browsers has been hotly debated for years. Some browsers support full profiles embedded in the images such as Safari, but IE and FF have been all over the map with it.

Here is the thing Rom, A.net REMOVES ALL METADATA, that is even the profile. So when you view on your browser, it is naked and the browser must make decisions on its own. JP.net PRESERVES metadata sdo when you view on browser, it sees the profile and applies it.

I totally see what's going on. I may need to do a little write up on this :-) thanks for the path to enlightenment... I know how all this works but forgot how A.net removing metadata, also removed color profile info from their images casing some browsers to fail.

Like I said, staying within gamut also helps by not bordering on the color space limits.

In any case, here are wonderful resources on the subject of Color Profiles and Color on the web using common Browsers

http://www.gballard.net/psd/go_live_...Gprofiles.html

and the direct link to the FireFox tests

http://www.gballard.net/firefox/