On Wed, Jul 19, 2000 at 11:53:30PM +1000, David Hodson <[EMAIL PROTECTED]> wrote:
> > No:
> No? If I render an object, and the edge of that object only covers
> half of a pixel, why does it need more than half the colour range?

I was talking about precision and not resolution.

> is that I could load an image file containing pre-multiplied alpha
> without being asked if the alpha should be un-multiplied. (Although
> I still think there's a useful distinction between pre-mult alpha
> and non-mult masks, and I would like to load an rgba image into
> Gimp and then add a mask layer.)

Pre-mulitplied alpha is a data representation which contains as much or less
information than the un-multiplied version.

The only reason to use pre-multiplied alpha is for speed, or ease-of-use.
(unless you argue that out-of-gamut values make sense). Since pre-multiplying
rgba images looses information (maybe a lot) there should be very good
reasons to switch the representation used to store the data.

As opposed to pre-multiplying image data to speed up display.

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