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Old 11-20-2002, 02:23 PM   #1
birdboydowns
A Ghoul
 
Join Date: Oct 2002
Posts: 17
Default Answer: What an Alpha is... (Transparency)

I am just about to start working on skinning, and came here for info. In order to "give back" I am gonna try to explain what Alphas & Masks are. (I work in TV graphics, so I have explained this one countless times):

<This is gonna be real Tech-geekish, but bare with me, it has a point> An image is saved using three different integers: Red, Green Blue. For simplicities sake, I am just gonna work with 16 bit color, so any color you use will actually have 3 values from 0-255(one for each of these three).

For example:
Red is R 255, G 0, B 0
Black is R 0, G 0, B 0

Now, if you have Photoshop, open an image and goto the "Channels" Tab (next to Layers). You will see that there are seperate channels for R, G, and B. Now, click on R (Red). Yyou will see a black&white image. This represents the Red value ONLY. Black equals a value of 0, and white equals a value of 255, and the various shades of gray are every thing inbetween. Nifty, eh?

Now, this is all fine and dandy, but what about if you want transperancy?

Well, that is what an alpha channel is.


An alpha channel is EXACTLY like the red, green and blue channel. black equals completely transparent, white equals completely visible, and the various shades of gray are every thing inbetween.

So, if you want a certain part to be 50% transparency, you should fill it with Pure Grey=127 (256 x 50% = 127)


Now, just play around with it... it is a weird concept, but once you get it, it is VERY simple.



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Well, I hope this makes sense... if it doesnt, sorry but Alpha channels are weird to most people.
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