[Gimp-user] What is the scale of Levels?
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. ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
Re: [Gimp-user] What is the scale of Levels?
On Sun, Aug 23, 2009 at 1:33 PM, 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) ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
Re: [Gimp-user] What is the scale of Levels?
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. ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
Re: [Gimp-user] What is the scale of Levels?
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 ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
Re: [Gimp-user] What is the scale of Levels?
On Tue, Aug 25, 2009 at 9:00 AM, 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? 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) ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
Re: [Gimp-user] What is the scale of Levels?
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 ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
Re: [Gimp-user] What is the scale of Levels?
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 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? > > 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) ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
Re: [Gimp-user] What is the scale of Levels?
On Tue, Aug 25, 2009 at 6:10 PM, Asif Lodhi wrote: > 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??? no. You should not aim to offend people. That is different from simply indicating what quote you find interesting or what your views are (though I would argue that the latter is somewhat irrelevant to a public mailing list). Your offense in this matter is quite as absurd as my taking offense to a passing man because he happens to be picking his nose as he passes. I'm not the arbiter of absolute truth, nor are you; it is only through free exchange of ideas that we human beings begin to grasp parts of the true nature of reality. Not by taking gratuitous offense at each other's ideas. > 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. Your initial post was not flaming. Now however, you have definitely passed over that line and *are* flaming (although you have certainly managed to be subtle.). My quote was an example of exactly the kind of content that tends to cause flamewars; posting it on a public mailing list is inappropriate IMO. By contrast, Darxus' is not flame bait -- not at all. > It's the quote. The quote is a quote, not an assertion of absolute truth about reality. Here's another one: “A society that will trade a little liberty for a little order will lose both, and deserve neither” -- Thomas Jefferson Hurt feelings are just hurt feelings. It's absolutely true that the more freedoms people have, the more they get hurt; that's just a simple matter of statistics -- the more things you can do, the more ways there are to get hurt. This does not justify reducing the number of things you can do; not in any way; nor do hurt feelings equate directly to any kind of non-trivial harm. Politeness and civility is justified; political correctness, OTOH, is sterile, stifling learning and the development of more nuanced ideas about reality. Hint: the above is my understanding only. > > 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. The quote I posted may be construed as offensive, as it is making an assertion about reality (which no doubt you find offensive, much to your detriment). The quote that Darxus has in his signature cannot reasonably be construed as offensive -- it is a quote of a character expressing a personal opinion about what kind of God he would find acceptable. It's not an argument that you should follow that example, or what *you* should find acceptable, nor is it an argument about what the state of reality is. Finding such a quote 'offensive' is as ridiculous as a Jew being offended at someone eating pork, or myself (who is allergic to dairy and doesn't eat it) being offended at someone drinking milk; It's disrespectful of people's choice to be able to live their lives according to their own individual understanding of life. You can say 'please stop it' all you like -- I at least, will listen only when you are asking me to stop doing something that honestly can be objectively considered as something that clearly should be stopped. I will never agree with stopping a practice simply because it *might* cause harm; there must be a clear case that it *will* cause harm. This has not been demonstrated (citing hurt feelings is *extremely* unconvincing. Feelings are like the weather. And we are not here to avoid hurting the feelings of people -- we are here to talk about using GIMP, with a *reasonable*, not overweening, level of regard for feelings.) David ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
