Re: Low level PNG image manipulation
Re: Low level PNG image manipulation
- Subject: Re: Low level PNG image manipulation
- From: Bill Dudney <email@hidden>
- Date: Sat, 8 Dec 2007 06:13:14 -0700
Hi Andrew,
Image I/O is written over libpng so it prob has the api that you need,
its probably just named differently. Following the trail of the
kCGImagePropertyIsIndexed property will likely lead you to what you
are looking for in terms of low level png stuff.
But before you dig too deeply into that I'd suggest you take a look at
Core Image, from your description it sounds like a custom filter would
do just what you are looking for.
http://tinyurl.com/2hhqg7
is a good tutorial for getting started from ADC.
HTH,
-bd-
http://bill.dudney.net/roller/objc
On Dec 8, 2007, at 1:16 AM, Andrew Ebling wrote:
I'm writing my first serious/hopefully useful Cocoa application
which manipulates PNG images, reducing the number of colours used
and paletising the image to reduce the file size.
In order to do this, I'll need to manipulate the PNG image file at a
fairly low level and I'm wondering what the best approach would be.
I've been searching the Developer Documentation for information on
using the PNG file format, but not found anything that looks useful.
Does anyone know if there is anything in the Cocoa API that would
help me do this? All I've found so far is CGImageProperties-
>kCGImagePropertyIsIndexed.
Or should I just revert to using libpng/zlib which are both open
source libraries written in C?
thanks,
Andrew
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