[Gimp-developer] stroking with gimp

2004-09-25 Thread Carol Spears
hi,

i have been playing with many generations of TheGIMP this morning.  i
compared the gimp's ability to make nice strokes and i found the results
to be interesting and revealing:
http://carol.gimp.org/files/stroke.png

can something be done to make stroking be at least as nice as it used to
be?  i was blaming libart, but it was explained to me that this was not
the cause.

simon is busy doing other things on the irc and such, perhaps we need a
volunteer to help?  raphael, you have experience with taking over
projects, perhaps you have some time.

carol

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Re: [Gimp-developer] stroking with gimp

2004-09-25 Thread Sven Neumann
Hi,

Carol Spears [EMAIL PROTECTED] writes:

 i have been playing with many generations of TheGIMP this morning.  i
 compared the gimp's ability to make nice strokes and i found the results
 to be interesting and revealing:
 http://carol.gimp.org/files/stroke.png

Well, the image alone doesn't make much sense. You will also have to
explain what you did to create it. A more elaborate comparison would
probably be helpful.

 simon is busy doing other things on the irc and such, perhaps we
 need a volunteer to help?  raphael, you have experience with taking
 over projects, perhaps you have some time.

It would really help if you could restrain of adding such useless and
inflamatory comments to your mails. That would allow us to actually
discuss the subject w/o getting into the next flamewar. But perhaps
that is what you are after?


Sven
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Re: [Gimp-developer] stroking with gimp

2004-09-25 Thread Simon Budig
Carol Spears ([EMAIL PROTECTED]) wrote:
 i have been playing with many generations of TheGIMP this morning.  i
 compared the gimp's ability to make nice strokes and i found the results
 to be interesting and revealing:
 http://carol.gimp.org/files/stroke.png

Interesting. I always assumed that the paintcore-based stroking has not
changed. I no longer have gimp 1.2 installed so I right now cannot check
why this apparently has degraded a bit.

 can something be done to make stroking be at least as nice as it used to
 be?  i was blaming libart, but it was explained to me that this was not
 the cause.

The primary reasons for the bad antialiasing is that the boundary of a
selection contains only horizontal and vertical lines. That is the
reason why the results improve dramatically when the boundary gets
converted to a path and then the path gets stroked.

Details are discussed in bug #50730
   http://bugzilla.gnome.org/show_bug.cgi?id=50730

What would help the stroking would be an automatic conversion of the
outline to a path and then stroking this. We cannot do this right now
since the selection to path functionality is implemented as a plugin and
the core must not depend on a plugin. I had a deeper look at potrace
(http://potrace.sf.net/) and have a stripped down version on my HD that
does its job in about 2000 lines of C, which is a somehow manageable but
still a lot of (sophisticated) code.

I intend to look further in this and when it turns out that this might
work I want to ask the potrace author if he has any concerns about the
inclusion of the algorithm into the GIMP.

However, this will take a while, especially since I'll try to avoid
touching computers more complicated than my digital camera next week
(vacation - whee!  :)

Bye,
Simon
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Re: [Gimp-developer] stroking with gimp

2004-09-25 Thread Carol Spears
On Sat, Sep 25, 2004 at 05:48:13PM +0200, Sven Neumann wrote:
 Carol Spears [EMAIL PROTECTED] writes:
 
  i have been playing with many generations of TheGIMP this morning.  i
  compared the gimp's ability to make nice strokes and i found the results
  to be interesting and revealing:
  http://carol.gimp.org/files/stroke.png
 
 Well, the image alone doesn't make much sense. You will also have to
 explain what you did to create it. A more elaborate comparison would
 probably be helpful.
 
understood.

the upper circles were stroked with the default setting of the current
stroke dialog.  the lower circles were stroked with the fuzzy 7 pixel
brush.  the stroking with gimp-1.2 did not have a default stroke option
like one finds in gimp2 so it is a simple stroking with the same 7 pixel
fuzzy brush.

  simon is busy doing other things on the irc and such, perhaps we
  need a volunteer to help?  raphael, you have experience with taking
  over projects, perhaps you have some time.
 
 It would really help if you could restrain of adding such useless and
 inflamatory comments to your mails. That would allow us to actually
 discuss the subject w/o getting into the next flamewar. But perhaps
 that is what you are after?
 
well, it is not inflamatory from me the source.  it is trying to work
with the same team.  simon is (by his own admission) studying human
behavior and i am not interested in interrupting.  i commend raphael for
his fine history with gimp things.

carol

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Re: [Gimp-developer] stroking with gimp

2004-09-25 Thread Sven Neumann
Hi,

Simon Budig [EMAIL PROTECTED] writes:

 What would help the stroking would be an automatic conversion of the
 outline to a path and then stroking this. We cannot do this right now
 since the selection to path functionality is implemented as a plugin and
 the core must not depend on a plugin.

The core can very well use a plug-in. It just needs to handle the case
that the plug-in is not available. This can be easily checked by
looking up the procedure in the PDB.

If it turns out that the potrace code would be useful for the GIMP, it
should probably be included as a plug-in and not been added to the core.


Sven
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Re: [Gimp-developer] stroking with gimp

2004-09-25 Thread Sven Neumann
Hi,

Carol Spears [EMAIL PROTECTED] writes:

 the upper circles were stroked with the default setting of the current
 stroke dialog.  the lower circles were stroked with the fuzzy 7 pixel
 brush.  the stroking with gimp-1.2 did not have a default stroke option
 like one finds in gimp2 so it is a simple stroking with the same 7 pixel
 fuzzy brush.

I cannot reproduce your brush-stroking result for gimp-2.0 then. Is
that a recent version of gimp-2.0 that you've been using? Does it
contain the fix for bug #147836?


Sven
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Re: [Gimp-developer] stroking with gimp

2004-09-25 Thread Carol Spears
On Sat, Sep 25, 2004 at 06:21:42PM +0200, Sven Neumann wrote:
 Hi,
 
 Carol Spears [EMAIL PROTECTED] writes:
 
  the upper circles were stroked with the default setting of the current
  stroke dialog.  the lower circles were stroked with the fuzzy 7 pixel
  brush.  the stroking with gimp-1.2 did not have a default stroke option
  like one finds in gimp2 so it is a simple stroking with the same 7 pixel
  fuzzy brush.
 
 I cannot reproduce your brush-stroking result for gimp-2.0 then. Is
 that a recent version of gimp-2.0 that you've been using? Does it
 contain the fix for bug #147836?
 
i am using gimp-2.0 from debian.

is there a reason that it would be fixed in the 2.0 branch and not in
the 2.1 branch?

carol

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Re: [Gimp-developer] stroking with gimp

2004-09-25 Thread Sven Neumann
Hi,

Carol Spears [EMAIL PROTECTED] writes:

  I cannot reproduce your brush-stroking result for gimp-2.0 then. Is
  that a recent version of gimp-2.0 that you've been using? Does it
  contain the fix for bug #147836?
  
 i am using gimp-2.0 from debian.
 
 is there a reason that it would be fixed in the 2.0 branch and not in
 the 2.1 branch?

Huh? Perhaps you should have another look at the image you posted
(http://carol.gimp.org/files/stroke.png). It shows different results
for gimp-2.0 and gimp-2.1. I can however not reproduce this. The
results I get for stroking look basically identical in gimp-2.1,
gimp-2.0 and gimp-1.2. I admit that the result isn't very satisfying
but I cannot reproduce your results. My guess is that you used a
different brush when creating the stroke with gimp-2.0.

The bug report I refered to should actually not affect your particular
example but I asked nevertheless just to be sure what versions we are
comparing here. As you could have easily found out by looking at
bugzilla, the fix for #147836 is in gimp-2.0.4 and of course it is
also in the HEAD branch.


Sven
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Re: [Gimp-developer] stroking with gimp

2004-09-25 Thread Carol Spears
On Sat, Sep 25, 2004 at 08:35:32PM +0200, Sven Neumann wrote:
 Hi,
 
 Carol Spears [EMAIL PROTECTED] writes:
 
   I cannot reproduce your brush-stroking result for gimp-2.0 then. Is
   that a recent version of gimp-2.0 that you've been using? Does it
   contain the fix for bug #147836?
   
  i am using gimp-2.0 from debian.
  
  is there a reason that it would be fixed in the 2.0 branch and not in
  the 2.1 branch?
 
 Huh? Perhaps you should have another look at the image you posted
 (http://carol.gimp.org/files/stroke.png). It shows different results
 for gimp-2.0 and gimp-2.1. I can however not reproduce this. The
 results I get for stroking look basically identical in gimp-2.1,
 gimp-2.0 and gimp-1.2. I admit that the result isn't very satisfying
 but I cannot reproduce your results. My guess is that you used a
 different brush when creating the stroke with gimp-2.0.
 
 The bug report I refered to should actually not affect your particular
 example but I asked nevertheless just to be sure what versions we are
 comparing here. As you could have easily found out by looking at
 bugzilla, the fix for #147836 is in gimp-2.0.4 and of course it is
 also in the HEAD branch.
 
well, due to the many concerns about how i made these images, there is
now a whole series of pngs/xcfs in this same directory, ending with:
http://carol.gimp.org/files/stroke4.png where the same selection is used
in all three gimp versions.

the selection has been saved in:
http://carol.gimp.org/files/stroke4.xcf and simon has made certain that
i did not use (even accidentally) different brushes.

simon and mitch are right now discussing changes to the paintcore which
might have affected this.  anyone can read this discussion here:
http://carol.gimp.org/gallery/journal/gimp-2004-09-25.txt

do you have changes in your version that no one else has?

carol

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Re: [Gimp-developer] stroking with gimp

2004-09-25 Thread Adam D. Moss
Sven Neumann wrote:
 My guess is that you used a
different brush when creating the stroke with gimp-2.0.
The top two look like they were stroked with a square
brush, which when applied to a circle is a pretty precise
recipe for what transpired...
--Adam
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Re: [Gimp-developer] stroking with gimp

2004-09-25 Thread Simon Budig
Adam D. Moss ([EMAIL PROTECTED]) wrote:
 Sven Neumann wrote:
  My guess is that you used a
 different brush when creating the stroke with gimp-2.0.
 
 The top two look like they were stroked with a square
 brush, which when applied to a circle is a pretty precise
 recipe for what transpired...

The top two were created using libart (i.e. postscript-like) stroking.
Since the boundary of the selection is composed of horizontal and
vertical lines, libart sees edges and uses the miter join style
to form the shape of the edges. The net effect is - as you saw - that it
looks a bit like stroking with a rectangular brush, but the effect stems
from a different source.

Bye,
Simon
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Re: [Gimp-developer] stroking with gimp

2004-09-25 Thread Simon Budig
Carol Spears ([EMAIL PROTECTED]) wrote:
 well, due to the many concerns about how i made these images, there is
 now a whole series of pngs/xcfs in this same directory, ending with:
 http://carol.gimp.org/files/stroke4.png where the same selection is used
 in all three gimp versions.
 
 the selection has been saved in:
 http://carol.gimp.org/files/stroke4.xcf and simon has made certain that
 i did not use (even accidentally) different brushes.

Actually I tried to explain to carol that the in some 2.0 version the
brush used for stroking is not always the same that is selected in the
brush dialog. Looking at stroke4.png does not convince me that carol
really used the brush the thought was using (I think it is bug #150716).

 simon and mitch are right now discussing changes to the paintcore which
 might have affected this.  anyone can read this discussion here:
 http://carol.gimp.org/gallery/journal/gimp-2004-09-25.txt

The behaviour seems to have been introduced by the patches by Henning
Makholm. It is spacing dependant and fiddeling with this avoids the
artefact. I have no real clue on that code and I won't work at it - at
least not for the next few days.

Bye,
Simon

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Re: [Gimp-developer] stroking with gimp

2004-09-25 Thread Sven Neumann
Hi,

Adam D. Moss [EMAIL PROTECTED] writes:

 The top two look like they were stroked with a square
 brush, which when applied to a circle is a pretty precise
 recipe for what transpired...

The top two are the result of stroking the selection outline using
libart. The strange outcome is because the selection boundary is not a
circle but rather a series of horizontal and vertical line segments.


Sven

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Re: [Gimp-developer] stroking with gimp

2004-09-25 Thread Simon Budig
Carol Spears ([EMAIL PROTECTED]) wrote:
 On Sat, Sep 25, 2004 at 09:26:12PM +0200, Simon Budig wrote:
  Actually I tried to explain to carol that the in some 2.0 version the
  brush used for stroking is not always the same that is selected in the
  brush dialog. Looking at stroke4.png does not convince me that carol
  really used the brush the thought was using (I think it is bug #150716).
 
 having been a user of gimp for several years and several versions, i
 have a few habits hardcoded into my work flow.
 
 for these examples, i actually opened the stroke dialog, closed the
 stroke dialog, chose the brush from the brush dialog and then reopened
 the stroke dialog, just to be certain.  meaning, i did not even rely on
 the dialog noticing that i had changed the brush.

Quoting from your IRC log: 

10:40 @carol and there is also a big difference between the brush
   stroking in 2.1 and in 2.0
10:42 @nomis I don't see a real difference between 2.0 and 2.1 here.
10:42 @nomis carol: maybe you've been tricked a bit by the problem
   that 2.0 doesn't always use the brush selected in the
   brush dialog for stroking. Make sure that you select the
   paint tool and the proper brush before stroking the
   selection.
10:44 @nomis (I cannot explain the different width of the stroke
   otherwise)

(Ok, the wording could have been clearer)
[...]

10:50 @carol nomis: not only did i make certain that i selected the
   proper brush before stroking. i made certain that the
   proper brush was selected before opening the dialog even
10:50 @nomis carol: switch to the paintbrush before stroking.

Apparently you missed that.

Bye,
Simon

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Re: [Gimp-developer] stroking with gimp

2004-09-25 Thread Sven Neumann
Hi,

Simon Budig [EMAIL PROTECTED] writes:

 Actually I tried to explain to carol that the in some 2.0 version the
 brush used for stroking is not always the same that is selected in the
 brush dialog. Looking at stroke4.png does not convince me that carol
 really used the brush the thought was using (I think it is bug #150716).

Yes, that's a nasty one. I got hit by that as well when I tried to
reproduce the strokes with 2.0.4. It is fixed in 2.0.5. That doesn't
mean that the stroking looks better but at least the stroking now uses
the brush one thinks it would be using.


Sven
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