Mod eyebrows -- how do they work?

Mostly out of curiosity, how does it work to have modifiable eyebrows on skins, where the skins themselves may or may not be modifiable?

As far as I can figure out, you have an alpha channel specifically for the eyebrows which lets through the colour you then set with the slide that controls eyebrow colour. Is that correct?

If so, are you limited to using some sort of default eyebrow alpha channel or at the very least default placement and/or shape, so that the system knows where to fill in that colour? Or can you make modifiable eyebrows of any shape and placement, and also allow the user full control over reshaping the brows via the sliders?

I guess I am partly trying to figure out what the potential downsides to doing eyebrows like this are, since it doesn't seem to be that common.

I've done them (and lipstick) as transparent areas on the skin texture. Make sure you put the default eyebrows behind the ones on your skin texture, so your buyers don't have to try to figure out how to use them.

Highlighting and shading is trickier - it'll look extreme on dark colors and faded on light ones or vice versa.

If you want to mess with a free one, I've got a neko skin with color-adjustable lips and eyebrows here. They're in the neon Neko sign.

http://slurl.com/secondlife/Sunwi%20Do/119/214/321/

My own skins and some others I've seen that have mod eyebrows use the Skin Color and Rainbow sliders to tint the eyebrows, not the eyebrow slider. Basically, the eyebrow shape is alpha'd out and slightly transparent and I provide a bald hair thingie to hide the default eyebrows if necessary (which are a really ugly shape, IMO)

This doesn't give perfect color control over the eyebrows unless you want them to be purple, but it does let you change them a little bit to suit your taste

Storm explains the process fairly well. I'll also add that it's more difficult to accurately depict natural hair follicles this way because any detail you attempt to keep (such as highlight) needs to be built into the alpha channel (much like the reflection on a windshield or soap bubble). A lot of that detail gets lost in the translation. None the less, there are a few advantages to working with tintable eyebrows.

Pros:

1. Some color adjustability on sliders
2. Reduced cost of texture development for eyebrow colors
3. Can work for other spots with textured hair, and lips too.

Cons:

1. Less realism than textured opaque eyebrows (no relative highlights or shadows)
2. Loss of contrast on certain skin tones (same reason as #1)
3. Color control is not great
4. Only works with opaque skins (can't adjust skin tone)
5. Confusing to the customer especially when multiple areas are not independently adjustable.

I experimented with adjustable eyebrows on my opaque skins and found them to lack a lot of the realism I needed for photosourced skin textures. Over all I found more reasons not to work with them than I did to work with them. I also polled some of the customers and they agreed.

Thanks, everyone. Your explanations and some experimentation has given me a good idea of how this works.

Its too bad, really, that the choice is either mod skin or mod eyebrows (or neither, of course) since both options add to versatility from a customer point of view. When you're picky, its so frustrating when you find the right skin and the eyebrow colour isn't what you need.

Oh, btw, Annyka, I really like Mellie, especially the natural.

Related question:

I recently bought a fab silvery blue skin, but I have no eyebrows and look like a freak! The skin is no mod. How do I, or is there a way, to put on some eyebrows, even if they're Slider brows? The shop where I bought the skin included a huge pack of free eyebrows, but from what I can tell, they appear "under" the blue skin and therefore not at all when viewed? Confused!

Thanks in advance.

Thank you Freyja! I'm really happy with how it came out

Oryx, as far as I know, if the skin is fully opaque, your pretty much out of luck, even if it was moddable, the eyebrows wouldnt show through. The eyebrows you bought are most likely a hair bodypart which change the shape of your brows (I know it doesnt make much sense)

I think your only real option, beside contacting the original skinner and convincing her to make you a custom skin with eyebrows, is to create prim eyebrows to lay over your brows.

*sigh* that's what I was afraid of. Thanks though!