Re: Layers and transparency Core Image
Re: Layers and transparency Core Image
- Subject: Re: Layers and transparency Core Image
- From: leenoori <email@hidden>
- Date: Sun, 24 Dec 2006 19:51:03 +0100
El 24/12/2006, a las 18:42, leenoori escribió:
No, I think in it's most basic form what I want to know if how I
can take a CIImage and uniformly apply an alpha value to it without
actually having to draw it. Like I said, I thought that
CIColorMatrix might be the right tack but I don't understand how to
use it.
I've found a good article explaining what a color matrix is,
conceptually:
http://www.c-sharpcorner.com/Code/2004/April/Transformations05.asp
Nothing to do with Cocoa or Core Image but the content seems
relevant. Same with this article:
http://www.adobe.com/devnet/flash/articles/
matrix_transformations_04.html
From this it appears that you can change the alpha component of an
image with a matrix like this:
1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 0.5
0 0 0 0
That would halve the alpha/opacity of the image.
Also found an example of CIColorMatrix in use:
http://trac.webkit.org/projects/webkit/browser/trunk/WebCore/kcanvas/
device/quartz/KCanvasFilterQuartz.mm?rev=17492
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