Suddenly my TGA's aren't clear

I've been using photoshop for i dunno how long.... I've also been uploading TARGAs... and all the way up until today they've shown up how they're supposed to.
But today, I uploaded a few TGA files, and they have a white background, instead of it being transparent. This is probably more of a photoshop question than an SL question...

Why would the TGAs I make in photoshop upload with a white background suddenly today?

Basically, the art file is text, and no background when I save as TGA.

Did you accidentally save them as 24-bit rather than 32-bit?

Is your alpha channel all white?

Why? I use compression all the time, no issues. TGA compression is lossless (unlike JPEG.)

Of course these days I upload PNGs mostly.

-peekay

I don't recommend compression on TGA's. In some cases, RLE compression can actually make the file bigger, not smaller. It works well for images without a lot of tonal variation, like illustrations or architectural drawings, but for things that are more photographic, it doesn't work very well at all.

To go a step further, I'll go on record as saying I'm not a fan of image compression at all in this day and age when storage space is incredibly cheap and practically unlimited. With the exception of web images, I find no justification for compression. Most compressed format techniques date back to the 80's or 90's, when storage space was at a premium. Today, the images haven't gotten any bigger, but hard drives and removable media certainly have.

An uncompressed 1024x1024 TGA is only 3 or 4 MB, depending on bit depth. One DVD can hold 1200-1600 of them. An average size hard drive can hold tens of thousands of them. An above average sized one can hold hundreds of thousands. And the drives get bigger practically every day. Why bother compressing?

i wouldnt use compression either, theres a change of some buggery like chosen stated, besides the SL client (as far as i understand it) compresses the image into jpg2k before it even leaves your machine

so filesize as you see it on your disk is a null and void point...

case in example:
back when LL let us upload 2048x2048 bustop-posters, uncompressed 24 bit bmp is roughly 12mb of data, my slower internet at the time had a 256kb upload speed, do the math and your looking at a handfull of minuets, rather than the 30-45 seconds it usually took before the image was uploaded (altho not rezed)

but osgeld why does it take (x) amount of time to appear in SL if its leaving my computer compressed?

simple ... the same reason it takes for freakin ever to download, the asset server

It might be ok when your file sizes is 3 or 4mb. But image sizes today ARE a lot bigger!

In photography, the minimum file size many clients accept is 50mb (my agency automatically rejects anything below that amount), and it's not unheard of to have 200 or 300mb images. Often we have to upload photographs online from remote areas in a 3rd-world country, with fairly slow links. It's just not practical do to all this without some form of image compression.

Another reason is file storage. Without compression, I'd need an additional 1 TB of storage every few months, and I don't shoot nearly as many pictures as most photographers! Forget doing remote backups with that kind of storage requirements.

There's nothing wrong in using lossless (or even lossy) compression when appropriate. Saying things like "don't use compression w/ alpha channels" sounds too dogmatic for me.

-peekay

thanks you guys, you hit the nail on the head.... all this time my photoshop was saving TGAs properly, so I never learned about the TGA related stuff. Somehow my photoshop settings just changed... ... but now I'm fixed back up
thanks

well overhere in the real world this is true, but in the relm of SL its pointless becuase your remote transfers are infact being compressed without user intervention

just to be a smartass i made a 200mb tga, even with rle compression your only saving a few KB so thats pretty much pointless, RLE is mainly for older computer systems, so they can handle a large (as in a few mb) image in the dinky amount of ram available.... it works simmilar to scanlines on a TV vs normal pixels

and nevermind the fact your never going to upload anything larger than 1 megapixel into SL let alone a 25megapixel image ... just keeping it in scope

Peekay, I think the reason we're in disagreement is we're approaching the question from two different points of view due to our professional backgrounds. You appear to be seeing it from the viewpoint of a photographer, whereas I'm looking at it from the perspective a real time digital artist. Just to add a little to what Osgeld said, you're right, Peekay, of course, that with photographs your image is going to be huge. You probably know this, but just for the sake of other readers who might not, images intended for good quality print should be 300 dpi or higher. That means an 8x10 photograph is going to be 2400x3000 pixels. Multiply that by 4 channels (CMYK), and you're looking at 27.5 MB. Even if you're working in RGB, which you really shouldn't be for print material, you're still talking 20.6 MB. Now you're starting to dive into where compression makes a lot of sense. Also, with that amount of data, most artifacting will be relatively hard to notice.

None of that, however, applies to TGA files, and especially not to the TGA's we use for SL. First, TGA is not a format photographers use. It's primarily used in 3D texturing and in video graphics. It's not well suited for print or for the web, the two main media for photos.

The texture images we use in SL are incredibly tiny compared to photographs. Even the largest texture we can use, 1024x1024, would be equivalent to only about 3.5 inch photo. I take it you don't routinely take photos that small, right?

Second, you're not likely to be using RLE compression on your photos. More likely you'll be using JPEG, JPEG2000, or one of the other algorithms that's relatively photo-friendly. The RLE compression that TGA's can use just doesn't work well for photos.

Anyway, I don't think anyone said "don't use compression with alpha channels". That would be a pretty silly philosophy. I won't speak for anyone else, but what I said was "I don't recommend compression on TGA files". In fairness, I guess I did misspeak when I said "I'm not a fan of image compression at all". That was too broad a statement. What I should have said was "I'm not a fan of compression for on-screen images". Clearly file size considerations for print images are still a real concern, and I should have mentioned that. So, I'm sorry for having left that out.

Put all that together, and I think it puts us both on the same page, does it not?

my only reason for saying 'no compression' was that, when i made my own first upload experiments, i had troubles too - upload not taking or glitchy content when it did... i found a thread someplace that said, 'targa/.tga, 32 bit, no compression' - which worked, of course... monkey see, monkey do, monkey passes along info...

as far as any personal choice for archival format, i stick to lzw compressed tiffs (ibm, though i'm a macker just in case ... or just layered psd's, with as many extra 'full composite' extras turned off as comfortable to my workflow... and lotsa dvrs.

PNG's where is this thingy that will let me upload PNG's? lol me want

@Chosen: you're absolutely right. The standard is still TIFF for photography so the file compression would be LZW. RLE is an option to compress individual layers. Press photographers need much smaller file sizes so they can use lossy formats such as JPEG (not an option for me though.) As Osgeld mentions above though, even for small textures, internally everything gets compressed by your typical 3D engine for performance reasons.

@Wilhelm: the Omega BETA open-source viewer supports PNG uploads.

-peekay

oo thanks i hope this ends up in the regular viewer over time