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 cou
Marc Lehmann wrote:
>
> On Wed, Jul 19, 2000 at 11:18:27PM +1000, David Hodson <[EMAIL PROTECTED]>
>wrote:
> > It's arguable that the information isn't there to start with.
>
> 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 ha
On Wed, Jul 19, 2000 at 11:18:27PM +1000, David Hodson <[EMAIL PROTECTED]> wrote:
> It's arguable that the information isn't there to start with.
No:
> A pixel with an alpha value of 0.5 will only contribute to half the
> colour of the pixel, so it only needs half the colour information.
Since
Thanks to everyone for the responses. A few comments:
Jay Cox wrote:
>
> David Hodson wrote:
> > the opinion of (for example) Jim Blinn, and Thomas Porter and Tom Duff.
>
> All three of whom come from a 3d rendered graphics background.
As do I.
> For compositing and image warping pre multipl
Calvin Williamson wrote:
> Eg He shows that if you want to downsample and then composite an image over
> a background, thats different from compositing first and then downsampling
> if you are using un-premultiplied images (you get different results that is).
> But with pre-multiplied images yo
On Tue, Jul 18, 2000 at 09:41:49PM -0400, Garry R. Osgood wrote:
> David Hodson wrote:
>
> > "Steinar H. Gunderson" wrote:
> >
> > > GIMP already does this (32-bit = RGBA, the `extra' 8 bits is an alpha channel,
> > > used for transparency information), and has done for a long time now.
>
> Calv
On Tue, Jul 18, 2000 at 09:41:49PM -0400, Garry R. Osgood wrote:
> David Hodson wrote:
> > Example: render an rgba image. (I was using some PovRay output; I
> > presume it does a reasonable job.) Now create a flat colour
> > background in the Gimp, lay the rgba image on top, and try to get
> > a c
David Hodson wrote:
> "Steinar H. Gunderson" wrote:
>
> > GIMP already does this (32-bit = RGBA, the `extra' 8 bits is an alpha channel,
> > used for transparency information), and has done for a long time now.
Calvin Williamson recommended "Image Composition
Fundamentals" by Alvy Ray Smith, for
On Tue, Jul 18, 2000 at 10:39:26PM +0100, I wrote:
> No the program which produced your example PNG image is broken.
> The PNG specification requires straight RGBA, pre-multiplied alpha is
> prohibited and this is spelled out several times. Gimp can't hope to
> interpret an invalid image correctl
On Wed, Jul 19, 2000 at 12:53:31AM +1000, David Hodson wrote:
> > Can you justify that (all images should be pre-multiplied)?
> > Or is this just your unsupported opinion?
>
> Well, that was attempted editorial humour to some extent, but it's also
> the opinion of (for example) Jim Blinn, and Tho
>It depends on what you are doing weather pre multiplied alpha is useful
>or not. For compositing and image warping pre multiplied alpha is great. for
>color correction pre-multiplied alpha just gets in the way. Since
>pre-multiplying the alpha does throw away a few bits of information my
>pref
David Hodson wrote:
>
> Nick Lamb wrote:
> >
> > On Sun, Jul 16, 2000 at 05:37:56PM +1000, David Hodson wrote:
> > > OK, this has been bugging me for some time. I'm convinced that Gimp's
> > > alpha handling is wrong, in more than a few places.
> >
> > OK, but please provide some concrete example
On Wed, Jul 19, 2000 at 12:53:31AM +1000, David Hodson <[EMAIL PROTECTED]> wrote:
> A hack? I thought it was a mathematically elegant representation of
> an image layer, which is why I see a reason to support it. I'm trying
AFAICS premultiplied alpha is a speed hakc and nothing more, for cases wh
Nick Lamb wrote:
>
> On Sun, Jul 16, 2000 at 05:37:56PM +1000, David Hodson wrote:
> > OK, this has been bugging me for some time. I'm convinced that Gimp's
> > alpha handling is wrong, in more than a few places.
>
> OK, but please provide some concrete examples...
> > To start with, there shou
On Sun, Jul 16, 2000 at 05:37:56PM +1000, David Hodson wrote:
> OK, this has been bugging me for some time. I'm convinced that Gimp's
> alpha handling is wrong, in more than a few places.
OK, but please provide some concrete examples...
> (Minor disclaimer - I don't have the code in front of me
"Steinar H. Gunderson" wrote:
> GIMP already does this (32-bit = RGBA, the `extra' 8 bits is an alpha channel,
> used for transparency information), and has done for a long time now.
OK, this has been bugging me for some time. I'm convinced that Gimp's
alpha handling is wrong, in more than a few
On Sat, Jul 15, 2000 at 02:29:02PM -0700, Michael O'Brien wrote:
>Anyone know if gimp will support 32-bit images in the near future?
GIMP already does this (32-bit = RGBA, the `extra' 8 bits is an alpha channel,
used for transparency information), and has done for a long time now.
/* Steinar */
>Anyone know if gimp will support 32-bit images in the near future?
Whad do you mean with "32 bit images"? 32 bit per channel? RGBA 32 bits (8
per channel)? CMYK?
The 8 per channel is already supported, CMYK is in limbo due the problems it
has (real RGB <-> CMYK, taking into account monitors, pr
Hola~
Anyone know if gimp will support 32-bit images in the near future?
MO
--
Michael O'BrienRenderMan Products
Pixar [EMAIL PROTECTED]
EINSTEIN: What I said is the fundamental, end-all, final
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