Dec 13, 2010 at 6:34 PM
Edited Dec 13, 2010 at 6:36 PM
I have read the article at the link and several others but my understanding of premultiplied ARGB is woolly - the term 'bitchmaps' has come to mind as I've been sitting here struggling with it :)
If a have some images on my hard drive could they be stored in a premultiplied format - or is that a meaningless question?
If I loaded an array with pixel data from an image (i.e. one element per pixel, not split into channels) could it be or not be in premultiplied format - or is that a meaningless question?
If I created 2 arrays both 4 times the size of my previous array and loaded the pixel data to each array split out into ARGB channels, then what would display in each array would depend on whether I premultiplied the RGB or not?
i.e. to one array I could extract just the straight ARGB information and in the other I could premultiply it - does this make any sense?
If it does, then what about a writeable bitmap, if I had a 10 pixel by 10 pixel writeable bitmap, are just 100 pixels stored in an array somewhere or is the pixel information split out internally in a premultiplied way and stored in separate channels, or
is the premultiplied value for a channel calculated and returned by default when I request it in some way?
If I have an array of non-premultiplied pixel data do I have to premultiply it before loading it to a writeable bitmap in order that it will display properly?
Or am I just thinking about this in entirely the wrong way?