On Sunday 21 December 2003 18:37, [EMAIL PROTECTED] wrote:
Raphaël Quinet [EMAIL PROTECTED] wrote:
(...)
I actually think Joao S. O. Buenos patch to the PNG plug-in is a
nice addition/work around the optimization problem - I have yet
to try it out, though.
I haven't tried it either, but
Raphaël Quinet [EMAIL PROTECTED] wrote:
But as you mention a proposed change, I will just repeat that this
discussion started because of a change that was introduced during the
feature freeze and that is (IMHO) controversial and goes against the
model that we should try to promote.
That's a
Patrick McFarland [EMAIL PROTECTED] wrote:
Conceptually, I agree that alpha = 0 means that the RGB value of the pixel
is undefined. Alpha = coverage; coverage = 0 means no pixel is there. Gone.
Inexistent. On the other hand, mask = 0 does NOT mean that the corresponding
pixel
On Tue, 16 Dec 2003 20:37:30 +0100, Henrik Brix Andersen [EMAIL PROTECTED] wrote:
On Tue, 2003-12-16 at 17:59, Raphaël Quinet wrote:
Basically, the model that we should promote is:
- layer mask= hiding mechanism, reversible
- alpha channel = pixels that are cleared have undefined RGB
On Tuesday 16 December 2003 21:44, Patrick McFarland wrote:
I tried PS to see how it handles Alpha. I became quite
frustrated. Once I deleted a part of the image and saved and
reloaded it, I found *no* way of increasing the opacity of
partially transparent pixels, not to mention totally
Raphael, can I ask you a thing?
You could maybe just add (or ask someone to add) a zero-out
transparent pixels on the layers menu.
This will make you possibly happy, and will NOT arbitrarily throw away
data that is relevant to more than one group of users as this thread
had shown.
Maybe, if
Hi,
Joao S. O. Bueno [EMAIL PROTECTED] writes:
You could maybe just add (or ask someone to add) a zero-out
transparent pixels on the layers menu.
There's a perl script in gimp-perl which does just that:
Image-Alpha-Clear Alpha
Sven
___
Ok, I managed to change my png plugin to handle cleaning out all
transparent pixels.
What do you say? Is it interesting to go in right now? If it is a PNG
recomendation, then it might be a nice add on, and it is small enough
to go in even now, before the first pre-2.0.
a 640x480 pix image
On Mon, Dec 15, 2003 at 10:45:56PM +, Adam D. Moss [EMAIL PROTECTED] wrote:
it's quite equivalent to letting the user take the saturation
knob down to zero and then coming back later, turning up
the saturation again and wondering where the original colours
To just throw in another personal
[EMAIL PROTECTED] ( Marc) (A.) (Lehmann ) wrote:
However, the layer effects people want is (in my eyes) exactly that:
apply some saturation effect to a layer that you can later change
without loss of fidelity.
And that'd be pretty groovy, and it'd work BECAUSE the
layer effect is conceptually (and
Hi,
On Tue, 2003-12-16 at 17:59, Raphaël Quinet wrote:
Basically, the model that we should promote is:
- layer mask= hiding mechanism, reversible
- alpha channel = pixels that are cleared have undefined RGB data,
not reversible (except for undo)
Breaking this model
Actually, this will be quite possible with the custom layer mode I
was cooking a couple months ago, and which I plan do revive to Gimp
2.2 ..
As an effect that applyes to the layer itself,like the dissolve
layer mode, instead of on combinations, it is doable there.
One will just have to write
[EMAIL PROTECTED] ( Marc) (A.) (Lehmann ) wrote:
To just throw in another personal opinion: The behaviour you describe
wrt. saturation would be hilarious. It's even implemented that way in
current gimp _until_ you say OK. After which you have to
(comparatively) clumsily have to re-adjust it.
If
Stephen J Baker wrote:
[EMAIL PROTECTED] ( Marc) (A.) (Lehmann ) wrote:
To just throw in another personal opinion: The behaviour you describe
wrt. saturation would be hilarious. It's even implemented that way in
current gimp _until_ you say OK. After which you have to
(comparatively) clumsily
On Tue, Dec 16, 2003 at 07:51:13PM +, Adam D. Moss [EMAIL PROTECTED] wrote:
[EMAIL PROTECTED] ( Marc) (A.) (Lehmann ) wrote:
While I sometimes find the erase tool conceptually difficult to use
(maybe because it's so unusual), the question is wether this is just a
weird added feature (as
Raphaël Quinet wrote:
On Tue, 16 Dec 2003 10:31:29 -0200, Joao S. O. Bueno [EMAIL PROTECTED] wrote:
You could maybe just add (or ask someone to add) a zero-out
transparent pixels on the layers menu.
[...]
I do not care (yet) about clearing the transparent pixels, destroying
color data, using
On Tue, Dec 16, 2003 at 05:55:06PM -0200, Joao S. O. Bueno [EMAIL PROTECTED] wrote:
Actually, this will be quite possible with the custom layer mode I
was cooking a couple months ago, and which I plan do revive to Gimp
Right, still I disagree in practise, and here is why:
While it can be
Stephen J Baker wrote:
I would rather hide that widget from Joe Public to avoid confusing him
than to unnecessarily destroy valuable data.
Let me say this one more time: If GIMP produces truly undefined data
where Alpha is zero - then GIMP will become utterly useless for
painting texture maps for
Raphaël Quinet [EMAIL PROTECTED] wrote:
You consider that in certain circumstances this behaviour could
be considered a bug.
Yes, because presenting undefined data to the user should be avoided.
I mostly agree with you, but there are reasons for me wanting the feature
implemented as the
On 17-Dec-2003, [EMAIL PROTECTED] wrote:
Conceptually, I agree that alpha = 0 means that the RGB value of the pixel
is undefined. Alpha = coverage; coverage = 0 means no pixel is there. Gone.
Inexistent. On the other hand, mask = 0 does NOT mean that the corresponding
pixel is inexistent, as
Raphaël Quinet wrote:
On Fri, 12 Dec 2003 14:41:08 -0600, Stephen J Baker [EMAIL PROTECTED] wrote:
MIPmapping works by creating successively reduced resolution images -
each (typically) half the resolution of the previous one.
When a MIPmapped image has alpha, this down-filtering produces
On Mon, Dec 15, 2003 at 07:43:39AM -0600, Stephen J Baker wrote:
But that assumes that alpha is pre-multiplied into the RGB's - which is
not the case for either DirectX or OpenGL's hardware texturing.
Both OpenGL and DirectX can handle premultiplied alpha just fine. Just use
additive blending
Hi Raphaël,
I think everyone has more or less had their say on the thread -
can I just sum up the salient points?
Raphaël Quinet wrote:
I agree. This is what the GIMP does and I was definitely not
suggesting to change this, so I think that you misunderstood what I
wrote. The GIMP will keep
David Neary wrote:
For the moment, unless I am mistaken, you are the only person to
have stated that they consider the current behaviour wrt
transparency flawed.
I'd just like to say that I somewhat agree with Raphaël.
Using alpha for 'hiding' and unhiding is conceptually wrong,
it's quite
Hi Stephen,
Stephen J Baker wrote:
What GIMP does now is just fine - what might be nicer would be some kind
of toggle to temporarily show the entire image as opaque (without actually
destroying the value of the alpha buffer).
Raphaël will probably kill me for advertising a feature he
Hi Raphael,
Raphaël Quinet wrote:
Well, I am still not sure about what was the real source of the
problem mentioned in that bug report.
Quite simply, Photoshop (according to the bug submitter) does not
pre-multiply RGB data by the alpha channel when saving, which
allows the complete data to be
(Sorry for yet another long mail. I will try to be more concise in
my other replies, by not repeating the points already stated here.)
On 09 Dec 2003 20:32:25 +0100, Sven Neumann [EMAIL PROTECTED] wrote:
Raphaël Quinet [EMAIL PROTECTED] writes:
2) For the pixels that have been obtained from
The value of the RGB of transparent pixels is crucial for applications
involving realtime MIPmapped textures...pretty much all 3D games for
example.
MIPmapping works by creating successively reduced resolution images -
each (typically) half the resolution of the previous one.
When a MIPmapped
On Tue, 9 Dec 2003 21:56:58 +0100, Simon Budig [EMAIL PROTECTED] wrote:
[...] We always had the general approach to empower the GIMP
user to do non-obvious stuff. Right now we don't discard RGB-information
when A=0 in the core, and stuff like Anti-Erase usually just works good
for power
On Wed, 10 Dec 2003 16:13:48 +0100, Dave Neary [EMAIL PROTECTED] wrote:
In any case, masks and alpha channels are also used to hide data across
sessions for several file formats (eg. png), and we have ven had a bug
report against the GIMP
(http://bugzilla.gnome.org/show_bug.cgi?id=82882)
Here is a long overdue and long-winded update to the discussion about
editing the alpha channel and how transparent pixels should be
handled...
One thing that has not been mentioned in this discussion so far is
that there are two kinds of transparent pixels: those that have been
made transparent
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