Painting 2-bit Alphas in Photoshop

[dustinbrown]

Can anyone share any techniques they use for painting 2-bit alphas in Photoshop for Alpha Testing? Painting in grayscale then converting the image mode to Bitmap often yields some crusty results, and it's pretty much impossible AFAIK to work in Bitmap mode since you don't have access to layers.

EDIT: I meant to put this in the Tech Talk forum. Tired brain.

[Kwramm]

adjust -> posterize (chose 2 colors), then fix individual pixels with the pencil tool. Or does anyone know a better way?

[JacqueChoi]

'Alpha Test' is for chumps.

'Alpha Safe' is where all the ballers are at.


But yeah, Pencil tool, Line tool (Anti-Aliased Checked off), and full contrast everything.

[dustinbrown]

Cool, thanks guys.

[fade1]

and by the way. it's called 1bit alpha. ;)
i suggest using the pencil tool 100% opacity, like stated before.

[dustinbrown]

You are correct.

http://www.paultosca.com/dominancewar/vgh/vgh_alfa_Test.jpg

[Frankie]

Layer adjustment > threshold gives you slightly more control than polarize.

Might be a good idea to make the source alpha 8 bit (then threshold layer adjust) incase you can use it later on... on the other hand it might be a waste of time :D

[Ghostscape]

I use curves to crush non-1bit into close to 1bit before the final conversion, it's more interactive and lets you dial in where the crush is happening.

[dustinbrown]

Yeah I tried using Curves and Levels to clip my 8-bit layer, but it still left a little halo in engine. The pencil works very well, you just have to spend a little time switching between black and white paint (X) until the hair tips look good. I'd rather do it manually anyway than let an adjustment layer handle things, since every pixel is important on a 1-bit image.

[gilesruscoe]

Threshhold does the trick pretty well i find!

[RexM]

To get rid of that halo, I usually duplicate the diffuse under another layer of the same diffuse, put on a gaussian blur, and duplicate that diffuse layer under the main diffuse.

[dustinbrown]

I don't quite follow. Wouldn't mind a visual example of that process when you have time.

[RexM]

Alright. Layer 1 and layer 1 copy are both identical. I would add a gaussian blur to layer 1, about 6-8, then duplicate layer 1 about 15 times. Then I would merge all those duplications.

http://img824.imageshack.us/img824/5276/examplex.jpg



Result. Definitely better than just doing an outer glow or something, since this way matches the colors perfectly.

http://img593.imageshack.us/img593/4377/example2w.jpg

[jimmypopali]

Nice approach. Kind of sampling the right pixels from the top layer, rather than picking one colour and filling the background.

[dustinbrown]

Oh I see what you did there. Thanks for the examples. xNormal has a dilation plugin for PS that will do edge padding. There's also the flaming pear plugin.

[Xenobond]

Heyo, you don't need a 1bit alpha mask to use alphatest. You will usually get better results with a full grayscale alpha.

Try it, you like it.

[perna]

Heyo, you don't need a 1bit alpha mask to use alphatest. You will usually get better results with a full grayscale alpha.

Try it, you like it.

This.

Try it with 3Point Shader: Enable test then adjust the opacity strength parameter.

and yeah, 2 bit is 4 colors:

00
01
10
11

[JohnnyRaptor]

Alright. Layer 1 and layer 1 copy are both identical. I would add a gaussian blur to layer 1, about 6-8, then duplicate layer 1 about 15 times. Then I would merge all those duplications.

http://img824.imageshack.us/img824/5276/examplex.jpg



Result. Definitely better than just doing an outer glow or something, since this way matches the colors perfectly.

http://img593.imageshack.us/img593/4377/example2w.jpg


theres a free photoshop plugin called flaming pearl that does edge padding, damn handy and faster

[Farfarer]

Usually you'll get an alphatest threshold slider/variable in the shader/material.

So you save the alpha as regular greyscale then twiddle that value to your liking.

[dustinbrown]

Eh I was using Marmoset for this particular thing. It uses the alpha channel in the diffuse color texture. I've had rotten luck with alphas in Marmo. Halos and sorting problems with Alpha Composite and they won't export properly in screen grabs, so I always have to use Alpha Test. I thought painting 1-bit out of the gate would mitigate against the issues I've had in the past.

When I try using an 8-bit alpha for alpha testing in Marmo, it just seems to get compressed down poorly. That's why I asked about painting in 1-bit. Figured it would give me more control over the outcome. I'll double check to see if it has that threshold you mentioned Talon. If there actually is a way for me to use 8-bit alphas in Marmoset, have them look great, and export in screen grabs, I'm all for it!

Thanks guys!

[Swizzle]

theres a free photoshop plugin called flaming pearl that does edge padding, damn handy and faster

Just use xNormal's Dilation filter. It's much better than Flaming Pear.