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gmc2
gmc2
Join Date 11/2003
+296

so tell me

June 29, 2009 5:45:42 PM from WinCustomize ForumsWinCustomize Forums

"premultiplied alpha".

what is it, what does it do, what does it look like without, what is it for, how do you do it???

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gmc2
vStyler
Join Date 11/2004
+919
Reply #1 June 29, 2009 6:07:10 PM
from WinCustomize ForumsWinCustomize Forums

There are a few images in SKS that need premultiplied alpha checked to look correct, Typically i use it on navigation arrow backgrounds and loggoff buttons.

 

To find out what it looks like with and without it.. turn it on... and off.

 

Not sure specifically how it works but heres some nice techy info

 

http://en.wikipedia.org/wiki/User:Lkesteloot/premultiplied_alpha

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gmc2
I.R. Brainiac
Join Date 05/2003
+281
Reply #2 June 29, 2009 6:19:14 PM
from WinCustomize ForumsWinCustomize Forums

The math for this operation is easy when the numbers are premultiplied:

R' = RF + (1 − AF)RB
G' = GF + (1 − AF)GB
B' = BF + (1 − AF)BB
A' = AF + (1 − AF)AB

The result is (0.75,0.5,0.5,0.75), which is the result of having each color's contribution to the pixel weighted by its area.

Clears thangs right up...dont it?

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gmc2
NightTrainthedark
Join Date 07/2003
+255
Reply #3 June 29, 2009 6:29:41 PM
from WinCustomize ForumsWinCustomize Forums

I was told there would be no math.

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gmc2
DjiRate
Join Date 08/2005
+62
Reply #4 June 29, 2009 7:51:43 PM
from WinCustomize ForumsWinCustomize Forums

The math for this operation is easy when the numbers are premultiplied:

R' = RF + (1 − AF)RB

G' = GF + (1 − AF)GB

B' = BF + (1 − AF)BB

A' = AF + (1 − AF)AB

The result is (0.75,0.5,0.5,0.75), which is the result of having each color's contribution to the pixel weighted by its area.

Clears thangs right up...dont it?

 

well thats why they call you the Brainiac...lol...what the hell is that?

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gmc2
storm347
Join Date 11/2003
+101
Reply #5 June 29, 2009 8:20:30 PM
from WinCustomize ForumsWinCustomize Forums

Quoting Night Train,
reply 3
I was told there would be no math.

 

 

math   turns around and runs from this thread

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gmc2
I.R. Brainiac
Join Date 05/2003
+281
Reply #6 June 29, 2009 8:28:59 PM
from WinCustomize ForumsWinCustomize Forums

what the hell is that?
I was told there would be no math.

 

Thats not math Craig...its an alien language...layouts for crop circles start with that.

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