Re: [Gimp-user] What is the scale of Levels?

2009-08-25 Thread Asif Lodhi
Hi David,

Obviously, you're more concerned about the mailing list. I know about
flame wars and never do that. I do 100% agree that I should have
emailed him personally on his own email address instead of this list
but it's really shocking to read your stern reply. Does the freedom to
say what you want to say really mean that you can say _whatever_ you
want??? And, that too on a public mailing list??? Is _that_ an
etiquette ? Aren't you hurting the feelings of so many thousands on
this list by posting such offensive language/quotes on a public
mailing list? Now who is hurting who? Can't you really see that that
very offensive quote can start many flame wars now and in future? It's
not me - I am not flaming. It's the quote.

I don't have anything personal against you or Darxus but posting such
offensive quotes on a public mailing list is way too offensive and can
really start way more than a flame war.

Please stop it.

-Asif


On 8/25/09, David Gowers 00a...@gmail.com wrote:
 On Tue, Aug 25, 2009 at 9:00 AM, Asif Lodhiasif.lo...@gmail.com wrote:
 Hi,

 On 8/23/09, dar...@chaosreigns.com wrote:
 I would believe only in a God that knows how to Dance. - Nietzsche

 Would you please stop using inappropriate language for God?

 Nietzsche also wrote God is dead. God remains dead. And we have killed him.
 
 http://en.wikipedia.org/wiki/God_is_dead
 No doubt you disagree with that (I do not, myself.). Regardless, the
 topic that you brought up (and especially the way you brought it up;
 you are not the arbiter of 'inappropriate language for God', nor does
 the way you presented your *opinion* as if it were *factual* speak
 well of your honesty.) is one that is commonly regarded as one that
 should not be brought up, as a matter of etiquette, on a public
 mailing list.

 If the issue of another person putting particular quotes in their
 email signature bothers you, I suggest you email them privately and
 leave all mailing-lists out of it.
 It's far less likely to result in a flame war than what you did do
 (post to a public mailing list attempting to get Darxus to change his
 behaviour on account of your *opinion*)

 
 Flaming
 Flaming is the practice of attacking people on a personal level.
 While flaming is relatively common on the internet, almost everybody
 will claim they're opposed to it. They may even flame you for having
 flamed someone. It's all really confusing, actually.

 However, there are some fairly obvious things. Responding to
 someone's analysis of the deficit crisis by telling them that they
 probably walk funny or weren't breast fed could easily classify as
 flaming. Making rude comments about an individual's sexual organs or
 religion would also probably classify.

 Personally, I stick to a simple rule: **I say nothing about
 anybody that I can not back up with facts. I do not comment about
 people's religions, their eating habits, whether or not they smoke,
 etc**. If I decide to comment about someone's level of intelligence, I
 make sure I have good examples to support my comment. But even then, I
 do this very rarely.
 
 **emphasis** added by me.

 http://songweaver.com/netiquette.html

 and

 
 If you should find yourself in a disagreement with one person, make
 your responses to each other via mail rather than continue to send
 messages to the list or the group. If you are debating a point on
 which the group might have some interest, you may summarize for them
 later. 

 http://www.dtcc.edu/cs/rfc1855.html (RFC 1855, the 'official' netiquette
 guide)
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Re: [Gimp-user] What is the scale of Levels?

2009-08-24 Thread Asif Lodhi
Hi,

On 8/23/09, dar...@chaosreigns.com wrote:
 I would believe only in a God that knows how to Dance. - Nietzsche

Would you please stop using inappropriate language for God?

-Asif
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Re: [Gimp-user] What is the scale of Levels?

2009-08-24 Thread David Gowers
On Tue, Aug 25, 2009 at 9:00 AM, Asif Lodhiasif.lo...@gmail.com wrote:
 Hi,

 On 8/23/09, dar...@chaosreigns.com wrote:
 I would believe only in a God that knows how to Dance. - Nietzsche

 Would you please stop using inappropriate language for God?

Nietzsche also wrote God is dead. God remains dead. And we have killed him. 
http://en.wikipedia.org/wiki/God_is_dead
No doubt you disagree with that (I do not, myself.). Regardless, the
topic that you brought up (and especially the way you brought it up;
you are not the arbiter of 'inappropriate language for God', nor does
the way you presented your *opinion* as if it were *factual* speak
well of your honesty.) is one that is commonly regarded as one that
should not be brought up, as a matter of etiquette, on a public
mailing list.

If the issue of another person putting particular quotes in their
email signature bothers you, I suggest you email them privately and
leave all mailing-lists out of it.
It's far less likely to result in a flame war than what you did do
(post to a public mailing list attempting to get Darxus to change his
behaviour on account of your *opinion*)


Flaming
Flaming is the practice of attacking people on a personal level.
While flaming is relatively common on the internet, almost everybody
will claim they're opposed to it. They may even flame you for having
flamed someone. It's all really confusing, actually.

However, there are some fairly obvious things. Responding to
someone's analysis of the deficit crisis by telling them that they
probably walk funny or weren't breast fed could easily classify as
flaming. Making rude comments about an individual's sexual organs or
religion would also probably classify.

Personally, I stick to a simple rule: **I say nothing about
anybody that I can not back up with facts. I do not comment about
people's religions, their eating habits, whether or not they smoke,
etc**. If I decide to comment about someone's level of intelligence, I
make sure I have good examples to support my comment. But even then, I
do this very rarely.

**emphasis** added by me.

http://songweaver.com/netiquette.html

and


If you should find yourself in a disagreement with one person, make
your responses to each other via mail rather than continue to send
messages to the list or the group. If you are debating a point on
which the group might have some interest, you may summarize for them
later. 

http://www.dtcc.edu/cs/rfc1855.html (RFC 1855, the 'official' netiquette guide)
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Re: [Gimp-user] What is the scale of Levels?

2009-08-24 Thread Patrick Horgan




Asif Lodhi wrote:

  Hi,

On 8/23/09, dar...@chaosreigns.com wrote:
  
  
"I would believe only in a God that knows how to Dance." - Nietzsche

  
  
Would you please stop using inappropriate language for God?
  

?? How is this inappropriate to note that Nietzche said that?

Patrick

  
-Asif
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Re: [Gimp-user] What is the scale of Levels?

2009-08-23 Thread Darxus
The answer appears to be:  sRGB, the color space to which gimp defaults
(unless you've specified another color space?).

The formula for converting sRGB levels to relative luminance is in the sRGB
spec.  A table of the Levels and their corresponding relative luminance
is here: http://www.chaosreigns.com/hdr/srgb/

This is very close to gamma 2.2 (a logarithm?), varying only slightly
for the sake of invertable binary math.

-- 
I would believe only in a God that knows how to Dance. - Nietzsche
http://www.ChaosReigns.com Guns save lives.
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[Gimp-user] What is the scale of Levels?

2009-08-22 Thread Darxus
I'm looking for a mathematical definition of this scale.  

http://docs.gimp.org/en/gimp-tool-levels.html says 0 is black and 255 is
white.  What's in between?  Is 7 double the brightness of 6?

What is the luminance / brightness of each of the levels?

Is it a logarithmic scale?  

-- 
Life is either a daring adventure or it is nothing at all.
- Helen Keller
http://www.ChaosReigns.com Guns save lives.
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Re: [Gimp-user] What is the scale of Levels?

2009-08-22 Thread David Gowers
On Sun, Aug 23, 2009 at 1:33 PM, dar...@chaosreigns.com wrote:
 I'm looking for a mathematical definition of this scale.

 http://docs.gimp.org/en/gimp-tool-levels.html says 0 is black and 255 is
 white.  What's in between?  Is 7 double the brightness of 6?

Have you not experimented with it? 7 is nowhere near being double the
brightness of 6.


 What is the luminance / brightness of each of the levels?

luminance (n) = n (or n/255. if you want luminance on a 0..1 scale)

 Is it a logarithmic scale?

no.
It's a nominally linear scale, which is then modified by gamma
parameter (if gamma == 1.0, that's no change). 0..255 simply
correspond to sRGB pixel intensity values directly. So if you want a
truly linear measurement of intensity, you need to apply the inverse
of the sRGB curve.

scipy used to provide an implementation of that -- see
http://mail.scipy.org/pipermail/scipy-svn/2007-February/000703.html
(rgbp2rgb function)
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