Blegh. Regarding PS7 alpha channels in SL

Quick question-

Do you folks have any idea why tga files imported from photoshop SEVEN.0 work in secondlife? (I believe theyre called embedded alpha channels but im not 100% sure.)

Apparently they really work nowhere else, I did all of my tattoos in this method.... I gather other residents have files done in the method used with PS7 as well.

Do you have any idea WHY these work in secondlife? I was about to change all of my tattoos to the proper way of creating alpha channels now that i have photoshop 7.0.1.... But its a lot of work so I figured i`d ask.

If you do know why it works in second life and don`t plan on changing it anytime soon then I will take my time redoing everything, if you guys are not sure why these "embedded alpha channels" work in SL, I would like to know so I can speed up the pace and fix all of my products before they just stop working in SL.


Thanks

I recall there was a bug in Photoshop 7.0 (not specific to SL)--which was fixed in 7.0.1 which allowed proper import of 32-bit TGA files with an alpha channel. Lot of links mentioning that bug are here:

http://www.google.com/search?as_q=photoshop+7.0+alpha+bug&num=100&hl=en&btnG=Google+Search&as_epq=&as_oq=&as_eq=&lr=&as_ft=i&as_filetype=&as_qdr=all&as_nlo=&as_nhi=&as_occt=any&as_dt=i&as_sitesearch=&as_rights=&safe=off

Moved to Design and Textures.

Thanks but that was definitely not my question.

I`m well aware there was a bug in PS7, im asking WHY do these files work in secondlife?

Oddly enough, the 7.0 ones did not work for me..... I had to get the 7.0.1 patch to make 'em work.

I guess i wasnt too clear (Still learning the correct way)

I think i was using something called "embedded alpha channels"

You dont actually make the alpha channel in the 'channels' tab, you just save it as a tga with the grey and white "checkers" still showing. These work fine in second life but not anywhere else.


Im wondering why these work in second life.... I have started redoing all of my tattoos the proper way now that I have PS7.0.1, but I would like to know if they have the slightest clue why they work in their program.

I'm not sure why PS 7.0 TGA's work with SL. You're right that they don't work with much else. SL's pretty unique in that way.

If I had to guess, I'd say maybe it's because SL was first released in 2003, which means it must have undergone substantial development in 2002, and 2002 hapens to have been the year that PS 7.0 was current. Well, I problably shouldn't say "year"; embedded alphas were really only in use for five months, March upto August 2002. Before the 7.0.1 patch came out that August, there was no way to know that Adobe was going to abandon them in favor of the standard (and thank god they did). I'd imagine SL's TGA reader was written some time during that five month window, so it was given the ability to interpret both standard and embedded alphas, and it's remained unchanged ever since.

If and when the image importing modules in SL ever get revamped, I'd be really suprised if they continue to support 7.0 style images.

Actually they do work other places. I have an aquarium screen saver program that uses them. I know not really useful for your purpose.

I haven't really delved too much into SL tech yet.. so I can't really help.

Yeah, there are a few programs out there that understand embedded alphas, but they're pretty few and far between. Unfortunately, when programs that don't know how to read them attempt to open them, the files tend to get corrupted. Once so damaged, the images are often impossible to fix. So be careful with those 7.0 style TGA's. They're fragile.

Interesting Chosen.









Still waiting for a lindens response..... Sigh

it shouldnt affect your current textures in sl, since when you upload a texture it converts them to JPEG2000. Butonce they fix it, any tga files with the embeded alpha wont work when uploading them.

If that`s true thats good news.........


Where can i confirm that statement at?


I know im not too learned when it comes to this but I do have a few modifyable clothings and when i go into edit appearance mode the texture used shows the grey and white checkers where its transparent, if it were converted into jpeg2000 wouldnt it be white around?

Wow, are you complaining about something actually working in SL? That's odd.

I emailed support instead. Hopefully I will get an official answer. And I hope Gattz is correct.

I wouldn't worry about that. Gattz is right that eveyrthing in SL is JPEG2000, once an image has been converted to that format, its source becomes irrelevant. Since the converter was able to understand the embedded alpha and turn it into transparency that JPEG2000 understands, the state of all existing images should be permanent. If they ever stop supporting embedded alphas, all that will happen is new images will have to be made with real alpha channels before upload.

Anyway, I hope you'll post whatever official answer you get. It would be interesting to hear a Linden tech view on this subject.

I don't actually know anything about the Photoshop 7 issues, however...

1) Once a file is imported to Second Life it is converted to jpeg 2000 and will continue to worrk within Second Life forever; the original format does not matter.

2) tga files are a funky format and there are a lot of different libraries out there for reading them. I don't expect us to change our importer any time soon, so if we currently support a particular tga file, we will likely continue to do so.

Thanks a bunch Steve, well that`s good news. Really good news. So I guess I don't have to redo my whole shop. But any new tats I make will be done the "correct" way.