Re: Obtaining unpremultiplied bitmap from PNG file
Re: Obtaining unpremultiplied bitmap from PNG file
- Subject: Re: Obtaining unpremultiplied bitmap from PNG file
- From: Shamyl Zakariya <email@hidden>
- Date: Wed, 13 Jun 2007 17:28:58 -0400
As far as I can tell, Cocoa simply won't give you non-premultiplied
bitmap data. The CG constant kCGImageAlphaLast ( IIRC ) is there, but
isn't actually implemented.
So, in my OpenGL apps I use libPNG directly. It's annoying to have to
do so, but what can you do?
email@hidden
On Jun 13, 2007, at 4:26 PM, Chiharu Hirono wrote:
I want obtain bitmap data from PNG file without premultiplied.
"NSBitmapImageRep Class Reference" (http://developer.apple.com/
documentation/Cocoa/Reference/ApplicationKit/Classes/
NSBitmapImageRep_Class/index.html) says:
If you need to work with unpremultiplied data, you should use
Quartz, specifically CGImageCreate with kCGImageAlphaLast.
But there are no way to obtain bitmap from CGImageCreate. How can I
get bitmap data?
C. Hirono
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