EQInterface Forums - Answer: What an Alpha is... (Transparency)

11-20-2002, 02:23 PM	#1
birdboydowns A Ghoul Join Date: Oct 2002 Posts: 17	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. --------------- Well, I hope this makes sense... if it doesnt, sorry but Alpha channels are weird to most people.

11-20-2002, 04:00 PM

Rolleo

A Snow Griffin

Join Date: Sep 2002

Posts: 58

Quote:

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

Unfortunetly, this type of transparency (actually should be called translucent cause it's partly visible, partly non visible) isn't supported, which sucks. The images that eq accepts need a single defined Alpha channel for transparency, and only supports ON or OFF levels. You can't have part of the image completely visible, another completely invisible, and another 50% visible.

11-21-2002, 10:33 AM	#3
birdboydowns A Ghoul Join Date: Oct 2002 Posts: 17	I was talking about alphas in general, not just for the GUI.

11-22-2002, 09:07 AM	#4
jobeken A Shissar Disciple Join Date: Sep 2002 Posts: 113	sigh never mind, not getting into this. __________________ Jobeken Xoner

01-27-2003, 03:00 PM	#5
Sinian A Ghoul Join Date: Dec 2002 Posts: 14	Thanks... Honestly, I've been guessing about what the Alpha channel is, but now I know. And Knowing is half the battle.

01-27-2003, 09:02 PM	#6
Lilcure A Snow Griffin Join Date: Aug 2002 Server: Cazic-Thule Posts: 59	Beg to differ but the cursor I made has 3 different transparency levels and they all work. Outer part opaque, inner part about 75% visible and a center line totally visible. Seems to work fine for me. __________________ Lilcure Halfling Archon of Mischief Shadowed Soul Cazic Thule

01-28-2003, 03:57 AM	#7
Rolleo A Snow Griffin Join Date: Sep 2002 Posts: 58	that post is over 2 months old, i've since learned otherwise and have already stated I was wrong in other threads. Thanks, though.

01-28-2003, 09:04 AM	#8
Lilcure A Snow Griffin Join Date: Aug 2002 Server: Cazic-Thule Posts: 59	Didn't even look at the dates hehe...sorry this wasn't meant as a slam at you in the slightest rolleo So many threads on here hard to keep up with them all sometimes.