Menu
▾
▴
Re: [Bodington-developers] CSS Processing
|
From: Antony C. <an...@sm...> - 2007-01-26 10:59:15
|
Just revisiting this as we still have the problem of 2 methods for setting colour in UI - one using style.css and the other using Bod code. Jon what was the conclusion from this debate and your coding? Do we have something that can be worked in to the bodington code without too much effort (or may be have already)? Would this fit with (Matthew's?) re-factoring of facility css? Antony On 7 Apr 2006, at 14:29, Jon Maber wrote: > Owen, > > the model you suggest _is_ much better than the usual HSV because, as > you say, it solves one of my big gripes, but the difference with that > and my model is the scaling of the saturation value. In my model a > color with a non-zero saturation and non-zero brightness which is > adjusted to zero brightness retains it's (relative) saturation value > and if the brightness is later transformed to a greater than zero > value the saturation is preserved (as is the hue.) The key thing > about my model (which perhaps you'd call Hue, percentage > Saturation[percentage in the sense of relative to the maximum possible > saturation possible for the given intensity and hue], Intensity) is > that any single value can be slid from 0 to 100% (or 0 to 360 degrees) > without changing the valid ranges of the other two values whereas in > the HSI (double conical model) the range of allowed saturation values > depends on the intensity and so saturation has to be clipped. > > The cylindrical model can be easily mapped onto the double-conical one > but the reverse is not true because the black and the white points > don't allow hue or saturation values. This means that any transform > that is implemented in the double conical space can be implemented in > cylindrical space but there are transforms in the cylindrical space > that can't be implemented in double conical space. > > I've produced a little Java app to play with the colour space and > speaking subjectively I like the way colours change as a single slider > is wizzed up and down. I'll have a go at changing it into an applet > and stick it on a web page. Then people can ignore the talk and the > maths and judge it on purely aesthetic grounds. > > Jon > > > Owen Davies wrote: > >> better to use HSI - Hue, Saturation, Intensty (aka IHS or HSB - Hue, >> Saturation, Brightness). This colour space can be visualised as two >> cones sandwiched together at their bases. The apex of the bottom cone >> represents [I min] (black) and the apex of the top cone represents [I >> max] (white). The line connecting the two represents the greyscale >> values (I). At each point along this line, H is undefined and S is 0. >> When I is 0, the horizontal plane of the colour space is greatest, >> because this is the plane where the bases of both cones meet. >> Therefore, S max is greater on this plane than anyhwere else in the >> colour space, thus the most vibrant colours are on this plane. >> Conversely, as you tend towards full brightness or minimum >> brightness, S max is reduced, until it eventually reaches 0. This >> means that as colours become lighter or darker, they automatically >> become less saturated. Furthermore, Jon's initial gripe with S does >> not apply, because adjusting saturation has no impact on H or I. This >> is a much more intutive way of representing colour than HSV. You >> simply think of it as a slider for brightness, a slider for >> saturation and one for hue, with brightness being the only variable >> that alters either of the other two (namely saturation). The Java >> Advanced Imageing (JAI) API has a class called IHSColorSpace >> (http://java.sun.com/products/java-media/jai/forDevelopers/jai- >> apidocs/javax/media/jai/IHSColorSpace.html) which conveniently >> manages colour space transformation from/to RGB. >> >> btw, microsoft and CSS3 use the HSI colour space. apple use HSV. >> Photoshop etc. use both. >> >> Anthony, I think you made a typo on that link because it's broken ;-) >> >> owen >> >> ----- Original Message ----- From: "Antony Corfield" >> <an...@sm...> >> To: <bod...@li...> >> Sent: Friday, April 07, 2006 11:04 AM >> Subject: Re: [Bodington-developers] CSS Processing >> >> >>> We will be holding a 3 day seminar in HSV processing here in late >>> June - to register, click on the link below: >>> http://www.whatthefeckishetalkingabout.com/ >>> >>> On 6 Apr 2006, at 19:37, Jon Maber wrote: >>> >>>> I must bow to your superior mathologicity. >>>> >>>> Many thanks for taking on this work package, good luck..... >>>> >>>> Jon >>>> >>>> Sean Mehan wrote: >>>> >>>>> Yes, all fine Jon, BUT what about compliance with the critical and >>>>> well known Hausdorff's Metric Top, you know: >>>>> >>>>> Let (S,d) be a metric space, and let X be the collection of all >>>>> nonempty bounded closed subsets of S. Let f:S * X -> R+ be defined >>>>> by f(s,B) = inf _(b in B) d(s,b), and let g: X * X -> R+ be given >>>>> by g (A,B) = sup_(a in A) f(a,B), and let delta(A,B) = max >>>>> {g(A,B),g (B,A)}. You must concern yourself with (X, delta)! Your >>>>> method clearly fails here! Pah! >>>>> >>>>> And for anyone wanting to quibble with my counterexample, yes, I >>>>> know, but I couldn't write the vector cross product adequately in >>>>> this crap test format, so had to resort to *. >>>>> >>>>> -s >>>>> >>>>> >>>>> On 6 Apr 2006, at 18:59, Jon Maber wrote: >>>>> >>>>>> Nearly all user colour preference work will operate in Hue- >>>>>> Saturation-Value space, not Red-Green-Blue space. However, the >>>>>> standard Java HSV colour space (which Bodington currently uses) >>>>>> is not very good so I've devised a better method. (Probably >>>>>> reinvented but it only took a couple of days work.) The standard >>>>>> HSV space is cylindrical where H is the perpendicular distance >>>>>> from the axis to the colour point, H is the angle of that line >>>>>> from the red plane and V is the distance up the cylinder. All >>>>>> of the bottom face is black. (which means that if V=0 then the >>>>>> colour is black regardless of the values of H or S) However, >>>>>> the top face has white only at the center and has bright >>>>>> rainbow colours around the edge. This means that if V is >>>>>> non-zero, V and H are kept constant and S is varied then not >>>>>> only does the perceived saturation change but the brightness >>>>>> does too. The method used to map the cube rgb space onto the >>>>>> cylinder is also dodgy since for certain values of H changing S >>>>>> distorts the perceived hue. >>>>>> >>>>>> My method also maps to a cylinder but the top face of the >>>>>> cylinder is completely white. This means that V==100% always >>>>>> produces white no matter what the value of H or S. It also >>>>>> means that if H and V are kept constant and S is varied, the >>>>>> perceived brightness and hue keep constant. This is acheived by >>>>>> two rotations of the rgb cube so that the white to black vector >>>>>> lines up with the z axis. Then the shape is distorted so that >>>>>> vectors which run from the z axis to the cube surface and which >>>>>> lie parallel to the x,y plane are stretched uniformly to unit >>>>>> length. The resulting cylinder is squashed down the z axis to >>>>>> unit length. >>>>> >>>>> >>>>> >>>>> >>>> >>>> >>>> >>>> ------------------------------------------------------- >>>> This SF.Net email is sponsored by xPML, a groundbreaking scripting >>>> language >>>> that extends applications into web and mobile media. Attend the >>>> live webcast >>>> and join the prime developer group breaking into this new coding >>>> territory! >>>> http://sel.as-us.falkag.net/sel? >>>> cmd=lnk&kid=110944&bid=241720&dat=121642 >>>> _______________________________________________ >>>> Bodington-developers mailing list >>>> Bod...@li... >>>> https://lists.sourceforge.net/lists/listinfo/bodington-developers >>> >>> >>> >>> >>> ------------------------------------------------------- >>> This SF.Net email is sponsored by xPML, a groundbreaking scripting >>> language >>> that extends applications into web and mobile media. Attend the live >>> webcast >>> and join the prime developer group breaking into this new coding >>> territory! >>> http://sel.as-us.falkag.net/sel? >>> cmd=lnk&kid=110944&bid=241720&dat=121642 >>> _______________________________________________ >>> Bodington-developers mailing list >>> Bod...@li... >>> https://lists.sourceforge.net/lists/listinfo/bodington-developers >> >> >> >> >> ------------------------------------------------------- >> This SF.Net email is sponsored by xPML, a groundbreaking scripting >> language >> that extends applications into web and mobile media. Attend the live >> webcast >> and join the prime developer group breaking into this new coding >> territory! >> http://sel.as-us.falkag.net/sel? >> cmd=lnk&kid=110944&bid=241720&dat=121642 >> _______________________________________________ >> Bodington-developers mailing list >> Bod...@li... >> https://lists.sourceforge.net/lists/listinfo/bodington-developers >> > > > > ------------------------------------------------------- > This SF.Net email is sponsored by xPML, a groundbreaking scripting > language > that extends applications into web and mobile media. Attend the live > webcast > and join the prime developer group breaking into this new coding > territory! > http://sel.as-us.falkag.net/sel? > cmd=lnk&kid=110944&bid=241720&dat=121642 > _______________________________________________ > Bodington-developers mailing list > Bod...@li... > https://lists.sourceforge.net/lists/listinfo/bodington-developers |