Photoshop CS Alpha - Tip #2

Ok, so if you're like myself, you banged your head on your desk for hours trying to figure out how to get transparency working in CS. Now that you've finally gotten that trick worked out, you're finding that many times your textures are getting a white haze around them!

Here's a little tip on how to eliminate it.


The haze is caused by how a TGA records transparency. If you have a partially-transparent layer (and no solid layer under it), CS renders it as if it was laid on a white background layer. That's what causes the white haze.

To fix it, make a duplicate of your image, and flatten it into a single layer. Copy that layer, so that you have two layers. Activate the top layer, then save as a .tga as you normally would. This time, when CS renders the image into a .tga, it'll use the bottom duplicated layer as the foundation rather than a white background. Once uploaded into SL, you should see a nice semi-transparent edge as you originally intended.

HTH,
- Newfie

Or create yout alpha and add a layer with 50% or more grey background when you save.

You can make a new layer beneath the image layer & floodfill it a darker colored version of the main color in the image layer. ie- a dark dark green-brown in the case of the plants example.

I like this one best- it seems quicker unless you have a gazillon colors at the edge of the alphas...

Or if you have more than one color make a new layer, use a Guassian blur, and then duplicate it and merge layers a few times (very fast, if you have an Action,) until it becomes opaque.

That works, and is quick, even if you do have a gazillion colors!

(I have a movie that shows this, and the PS Action that you can just download and install, in a video tutorial on my site, as mentioned in another thread.)

Hope this helps!

Robin (Sojourner) Wood

I call that white haze a halo and have seen it ruin so many images in SL. Another hint for getting rid of these is to go to Layer>matting>defringe. Default is 1 pixel but you can increase that to 2, this tells PS to stop trying to blend the edges into a background that doesn't exist.

(Be careful using too dark a background layer for blending those edges. Too dark will give you dark edges on your lighter shaded layers. I know, I've done it...lol)

Great tip Wisper. I didn't know about that setting!

If you open your image in Paint Shop Pro 8 or 9 then save it you'll end up with an alpha channel layer called "Transparency", visible when you reopen the file in Photoshop. You need to make a minor change to the picture while in PSP to make sure the alpha is saved properly. Then all you need to do is drop a matching background layer behind your image, and save it as a 32-bit tga.

Umm, I'm sorry, Wisper, but that's not what Defringe does.

From the Adobe on-line manual; "Defringe replaces the color of any fringe pixels with the colors of nearby pixels containing pure colors (those without background color)."

It doesn't have anything at all to do with blending or transparency, really, whether there is something to blend with or not. (Although I can see why you might get that impression.)

Honestly, in my opinion, it's essential to put a color-matching background behind your images when taking them from Photoshop into Second Life, since (unless you are using PS 7?) it will be flattened onto white. Fortunately, it takes only a few seconds to do this, using whichever technique from the earlier posts fits your particular image.

And yes, Wisper is correct when stating that a black halo can be just as bad.

If you have an image on a transparent background in Photoshop, all you need to do is hold down Command/ctrl, click on the Layer Thumbnail, and go to Select > Save Selection. That makes your alpha channel, as perfect as you could wish for, with partial transparency and eveerything.

Color match the background, save as a 32 bit Targa, and you're golden.

I always use the colored background as well ...

However, quoting NAPP's Tips book

"Get Rid of Fringe Pixels
Sometimes when you combine multiple images for a collage, you see a slight fringe around the edges of layers that are copied from other images. In many cases you can remove that fringe by going to Layers>Matting>Defringe. Try using the default setting of 1. That will often do the trick, but if not, choose Undo (from the Edit menu) and go back and try a Defringe setting of 2."

It was this that always made me think it was helping with the edges of the selection for the targa as well...

Yep, as I said, I can see why people would think that. When you are making something like a collage, or post-processing, it certainly looks like that's what it's doing.

I found it wasn't when I was zoomed in really closely on something once, and noticed that the transparency wasn't changing at all, but the colors of the pixels were. That's when I looked it up.

Robin (Sojourner) Wood
http://www.robinwood.com