Alpha channel and transparency of character graphics

[Alessio]

I've gotten to the stage of dealing with the graphics now... and up comes the question: How are those of you involved with graphics handling the transparent parts of a character?

Do you just have transparency outside the hard edges of the drawing (resulting in a pixellated outline), or are you using gradual transparency along the drawing's outer line to get a smoother anti-aliasing effect?

The simple (pixellated) transparency I manage, but how do you achie the more continuous one? Which programs (GIMP?) and how much work is it? I've searched for tutorials about this, but only found the general theory. Basically I'd have to mix the character's black outline with an alpha-channel color (more alpha towards the outside)?

Thanks for your suggestions!

[Icekiss]

Gimp should give you this gradual transparency automatically, whenever you draw a line, or apply some other tool. It would actually be much harder to get it do hard transparency.

But I am no artist, and don't know which process you use...

[Alessio]

I'm drawing on paper (b/w), then scanning and coloring. Earlier I'd used Pixia since I like its user interface, but it doesn't offer alpha channels.

The black lines are scanned and thus not drawn with GIMP, so I'd probably have to redraw them? Or can you actually select the area around the character and start from there?

[Iaman]

I'm not too sure about GIMP, because I've never used it, but if it has similar features to photoshop, you can do this.

Invert Colors

Layer Styles ----> Outer Glow(White)

Invert Colors

That should give you a nice black gradual fade. I only do it that way because I have Photoshop Elements 2, where you can't set the outer glow color(it's only white). But if you do it that way, it should work. Otherwise, if you can set the outer glow color, just use Outer Glow with black.

Of course, this is assuming that GIMP has an outer glow effect...

[Alessio]

Thanks, I'll have to try that. However, I'd have to apply the gradual fade to the outline only, not to the whole background - otherwise the character would always carry around a kind of shade.

I guess I'll just have to sit down and experiment a bit. ^_^

[Alessio]

There seems to be a "Color to Alpha" functionality in GIMP to replace a real color with Alpha information. That sounds very much like what I'd need. Now if I could just find those five minutes to actually do it... ;_;

And also found a tutorial now that I know the name of the function:
http://www.gimp.org/tutorials/Changing_ ... d_Color_1/

[Watercolorheart]

What I use ... Flash to make a high-quality PNG with 24bit & alpha channel ... actually will convert into GIFs with partial transparency at the edges. Looks pretty neat.

Any vector utility should be able to give you clean, desirable lines as well. I suggest SWISH.

[Alessio]

By now I can confirm GIMP is a breeze to use for this kind of stuff. Transparency works great, and coloring the scanned art is really easy too. Just took a while to work it out. ^_^