I am getting some unusual results sometimes when i use the Neon Edge Detection Filter parameters: 9, 3.0 Is there someone I could correspond directly with to send an example original photo and the processed one. I did mention this briefly about a year ago but wish to go into it in more depth. Thank you. *- david * *Regards,David RosenthalCitySoft, Inc.(917) 922-2113* *www.citysoftinc.com <http://www.citysoftinc.com>* On Mon, Feb 15, 2016 at 2:24 AM, <gimp-developer-list-request@xxxxxxxxx> wrote: > Send gimp-developer-list mailing list submissions to > gimp-developer-list@xxxxxxxxx > > To subscribe or unsubscribe via the World Wide Web, visit > https://mail.gnome.org/mailman/listinfo/gimp-developer-list > or, via email, send a message with subject or body 'help' to > gimp-developer-list-request@xxxxxxxxx > > You can reach the person managing the list at > gimp-developer-list-owner@xxxxxxxxx > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of gimp-developer-list digest..." > > > Today's Topics: > > 1. Re: Adding better LCH support to GIMP 2.10 (Elle Stone) > 2. Re: Adding better LCH support to GIMP 2.10 (Sven Claussner) > 3. Re: Adding better LCH support to GIMP 2.10 (Elle Stone) > 4. Re: Adding better LCH support to GIMP 2.10 (Partha Bagchi) > 5. Re: Adding better LCH support to GIMP 2.10 (?yvind Kol?s) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Sun, 14 Feb 2016 12:44:04 -0500 > From: Elle Stone <ellestone@xxxxxxxxxxxxxxxxxxxx> > To: gimp-developer-list@xxxxxxxxx > Subject: Re: Adding better LCH support to GIMP 2.10 > Message-ID: <56C0BCE4.2020809@xxxxxxxxxxxxxxxxxxxx> > Content-Type: text/plain; charset=windows-1252; format=flowed > > I received an email complaining that it was not true that as located on > the LCH color wheel, sRGB Blue was blatantly violet, sRGB Red was on the > orange side of red, sRGB Green was on the yellow side of green, and sRGB > Yellow as on the green side of yellow. > > There is a sliver of truth in the complaint. On the LCH color wheel, my > statement is true. > > However, LAB/LCH was designed to measure color differences, not to serve > as a color appearance model, even though it often gets used as such. > Also the LAB color space is particularly bad when it comes to dealing > with blues and violets. > > For comparison, here are JCH and LCH values reported using the ArgyllCMS > xicclu tool: > > Hue JCH/LCH > sRGB Blue 301 [LCh] > sRGB Blue 273 [JCh] (still on the violet side of blue, but not > blatantly violet) > > sRGB Green 134 [LCh] > sRGB Green 140 [JCh] (not as far towards yellow) > > sRGB Red 41 [LCh] > sRGB Red 32 [JCh] (not as far towards orange) > > sRGB Yellow 100 [LCh] > sRGB Yellow 111 [JCh] (farther towards green) > > > As you can see from these values, according to JCH model, sRGB Blue is > still on the violet side of the JCH color wheel. But it's not nearly as > far on the violet side of the JCH color wheel as it is on the LCH color > wheel. > > For both color wheels, sRGB Green is on the yellow side of green, sRGB > Red is on the orange side of red, and sRGB Yellow is on the green side > of yellow. > > If you would like to check for yourself: > > Here's the handprint.com CIECAM (JCH) color wheel: > http://www.handprint.com/HP/WCL/cwheel06.html > > Here's the handprint.com CIELAB (LCH) color wheel: > http://www.handprint.com/HP/WCL/labwheel.html > > Here's the xicclu commands for checking the LCH/JCH values for sRGB > colors using an sRGB ICC profile: > > xicclu -ir -pJ sRGB-elle-V2-g10.icc > xicclu -ir -pL sRGB-elle-V2-g10.icc > > Here's a link to the xicclu documentation: > http://argyllcms.com/doc/xicclu.html > > Here's a link to download ICC profiles: > http://ninedegreesbelow.com/photography/lcms-make-icc-profiles.html > > It would be very nice if GIMP users had a way to pick colors using the > LCH color wheel or better yet the JCH color wheel. Either color space is > a vast improvement over the pathetically inadequate HSV. > > Best, > Elle > > > > ------------------------------ > > Message: 2 > Date: Sun, 14 Feb 2016 21:56:19 +0100 > From: Sven Claussner <scl.gplus@xxxxxxxxx> > To: gimp-developer-list@xxxxxxxxx > Subject: Re: Adding better LCH support to GIMP 2.10 > Message-ID: <56C0E9F3.3060605@xxxxxxxxx> > Content-Type: text/plain; charset=windows-1252; format=flowed > > Hi, > > @Elle: you are speaking here of the JCH color model (or space) and > mentioned > on your website [1] that JAB and JCH have outdated LAB and LCH > (which are often considered the high end image editing color > spaces/models). > Searching a while for more information about JCH I found only very few > information, even not on other color management and FOSS graphics devel > mailing lists. Only on the PXLab website [2] I see a short description: > > JCH:=The CIE Color Appearance Model (1997) with viewing and scene > conditions > to be defined separately. > > I'm failing to understand all its implications. > Can you tell us more about JCH and JAB and why you consider it to > be a good choice, please? What about LAB and LCH then? > Does somebody else here know more about it? > > Thank you in advance > > Sven > > > [1] > > http://ninedegreesbelow.com/photography/high-bit-depth-gimp-tutorial-edit-tonality-color-separately.html > > [2] > > http://irtel.uni-mannheim.de/pxlab/doc/api/de/pxlab/pxl/ColorSpaceCodes.html#CS_JCh > > > > ------------------------------ > > Message: 3 > Date: Sun, 14 Feb 2016 18:33:39 -0500 > From: Elle Stone <ellestone@xxxxxxxxxxxxxxxxxxxx> > To: Gimp-developer <gimp-developer-list@xxxxxxxxx> > Subject: Re: Adding better LCH support to GIMP 2.10 > Message-ID: <56C10ED3.3070000@xxxxxxxxxxxxxxxxxxxx> > Content-Type: text/plain; charset=windows-1252; format=flowed > > On 02/14/2016 03:56 PM, Sven Claussner wrote: > > Hi, > > > > @Elle: you are speaking here of the JCH color model (or space) and > > mentioned > > on your website [1] that JAB and JCH have outdated LAB and LCH > > (which are often considered the high end image editing color > > spaces/models). > > Searching a while for more information about JCH I found only very few > > information, even not on other color management and FOSS graphics devel > > mailing lists. Only on the PXLab website [2] I see a short description: > > > > JCH:=The CIE Color Appearance Model (1997) with viewing and scene > > conditions > > to be defined separately. > > > > I'm failing to understand all its implications. > > Can you tell us more about JCH and JAB and why you consider it to > > be a good choice, please? What about LAB and LCH then? > > I can't tell you very much about JCH/JAB because I'm still trying to > figure it all out myself. > > You might try plowing your way through this PDF: > http://rit-mcsl.org/fairchild/PDFs/AppearanceLec.pdf > > This page has links to some equations: > https://en.wikipedia.org/wiki/CIECAM02 > > This page briefly talks about color appearance models in more > down-to-earth terms: > http://www.rit-mcsl.org/fairchild/WhyIsColor/Questions/4-8.html > > An internet search on terms like Color appearance model, Mark Fairchild, > and CIECAM02 will turn up a lot of material. None of it is easy reading. > > LAB answers the question "how far apart do colors have to be before the > average human observer will say 'those are different colors'". The > "home" of LAB was for use with quality control for colors in textiles, > printing, and such. LAB wasn't designed to be used as a color space for > editing, but it works pretty well for a lot of different editing tasks. > > A full understanding of LAB would require understanding the kinds of > experiments that were done to map out "when is color X different enough > from color Y to be seen as visually different?" I have no idea what kind > of experiments were done or how the mathematical model was constructed > from the experimental results. But the resulting equations to convert > from XYZ to LAB and then LCH are pretty straightforward. > > Color appearance models are designed to answer a very different and much > more complicated set of questions. They try to answer questions like > "How to describe colors?", "Why does the appearance of one color change > when juxtaposed next to another color?", and "Why does a surface look > the same color even when the light shining on it changes drastically > (for example from bright daylight to deep shade or to tungsten lighting, > or even in the shadow side of an object)?". > > These are complicated questions, being answered using complicated > research and complicated resulting models described by complicated sets > of equations. Also color appearance models are a very active area of > ongoing research, so what's considered really good today might be > superceded tomorrow. > > My reasons for suggesting that for use in GIMP (1)LAB/LCH is good and > (2)JAB/JCH is probably better are so simplistic that you'll all just laugh: > > 1. Bruce MacEvoy's handprint.com website on watercolor pigments switched > from using LCH to using JCH to give paint pigment colors, and I respect > Bruce MacEvoy as an authority on giving useable values for paint > pigments: http://handprint.com/HP/WCL/water.html, > http://handprint.com/LS/CVS/color.html > > 2. Mark Fairchild seems to think CIECAM02 is a pretty good color > apperance model, though again this is a field of active research, and > much of what Mark Fairchild writes goes right over my head. > > 3. ArgyllCMS and LCMS already incorporate the equations for JAB/JCH in > their code, as does RawTherapee, so it has to be not too difficult to > code up for GIMP. But my (very limited) efforts to make sense of the > ArgyllCMS/LCM/RT code have so far been unsuccessful. > > I find the LCH blend modes, color picker, and Hue-Chroma tool to be > incredibly useful. The few people who've written to me about using my > patched GIMP seem very enthusiastic. > > JCH apparently is more accurate than LCH for describing colors. I'm not > sure how much difference the "more accurate" would make in the digital > darkroom. It would be nice to be able to give JCH a try, but in the > meantime I can't imagine going back to editing without LCH. > > > Does somebody else here know more about it? > > No doubt even my short description above needs a lot of corrections! > > > > > Thank you in advance > > > > Sven > > > > > > [1] > > > http://ninedegreesbelow.com/photography/high-bit-depth-gimp-tutorial-edit-tonality-color-separately.html > > > > > > [2] > > > http://irtel.uni-mannheim.de/pxlab/doc/api/de/pxlab/pxl/ColorSpaceCodes.html#CS_JCh > > > > > > _______________________________________________ > > gimp-developer-list mailing list > > List address: gimp-developer-list@xxxxxxxxx > > List membership: > > https://mail.gnome.org/mailman/listinfo/gimp-developer-list > > List archives: https://mail.gnome.org/archives/gimp-developer-list > > > > > > ------------------------------ > > Message: 4 > Date: Sun, 14 Feb 2016 19:25:44 -0500 > From: Partha Bagchi <partha1b@xxxxxxxxx> > To: Elle Stone <ellestone@xxxxxxxxxxxxxxxxxxxx>, Sven Claussner > <scl.gplus@xxxxxxxxx> > Cc: Gimp-developer <gimp-developer-list@xxxxxxxxx> > Subject: Re: Adding better LCH support to GIMP 2.10 > Message-ID: > <CAOW9c=9+UuSCbbTeWeE32rLq036vtefyguxPG= > VanDOy3ui9PA@xxxxxxxxxxxxxx> > Content-Type: text/plain; charset=UTF-8 > > First hit when you google: > http://www.colourphil.co.uk/lab_lch_colour_space.shtml > > > On Sun, Feb 14, 2016 at 6:33 PM, Elle Stone < > ellestone@xxxxxxxxxxxxxxxxxxxx> > wrote: > > > On 02/14/2016 03:56 PM, Sven Claussner wrote: > > > >> Hi, > >> > >> @Elle: you are speaking here of the JCH color model (or space) and > >> mentioned > >> on your website [1] that JAB and JCH have outdated LAB and LCH > >> (which are often considered the high end image editing color > >> spaces/models). > >> Searching a while for more information about JCH I found only very few > >> information, even not on other color management and FOSS graphics devel > >> mailing lists. Only on the PXLab website [2] I see a short description: > >> > >> JCH:=The CIE Color Appearance Model (1997) with viewing and scene > >> conditions > >> to be defined separately. > >> > >> I'm failing to understand all its implications. > >> Can you tell us more about JCH and JAB and why you consider it to > >> be a good choice, please? What about LAB and LCH then? > >> > > > > I can't tell you very much about JCH/JAB because I'm still trying to > > figure it all out myself. > > > > You might try plowing your way through this PDF: > > http://rit-mcsl.org/fairchild/PDFs/AppearanceLec.pdf > > > > This page has links to some equations: > > https://en.wikipedia.org/wiki/CIECAM02 > > > > This page briefly talks about color appearance models in more > > down-to-earth terms: > > http://www.rit-mcsl.org/fairchild/WhyIsColor/Questions/4-8.html > > > > An internet search on terms like Color appearance model, Mark Fairchild, > > and CIECAM02 will turn up a lot of material. None of it is easy reading. > > > > LAB answers the question "how far apart do colors have to be before the > > average human observer will say 'those are different colors'". The "home" > > of LAB was for use with quality control for colors in textiles, printing, > > and such. LAB wasn't designed to be used as a color space for editing, > but > > it works pretty well for a lot of different editing tasks. > > > > A full understanding of LAB would require understanding the kinds of > > experiments that were done to map out "when is color X different enough > > from color Y to be seen as visually different?" I have no idea what kind > of > > experiments were done or how the mathematical model was constructed from > > the experimental results. But the resulting equations to convert from XYZ > > to LAB and then LCH are pretty straightforward. > > > > Color appearance models are designed to answer a very different and much > > more complicated set of questions. They try to answer questions like "How > > to describe colors?", "Why does the appearance of one color change when > > juxtaposed next to another color?", and "Why does a surface look the same > > color even when the light shining on it changes drastically (for example > > from bright daylight to deep shade or to tungsten lighting, or even in > the > > shadow side of an object)?". > > > > These are complicated questions, being answered using complicated > research > > and complicated resulting models described by complicated sets of > > equations. Also color appearance models are a very active area of ongoing > > research, so what's considered really good today might be superceded > > tomorrow. > > > > My reasons for suggesting that for use in GIMP (1)LAB/LCH is good and > > (2)JAB/JCH is probably better are so simplistic that you'll all just > laugh: > > > > 1. Bruce MacEvoy's handprint.com website on watercolor pigments switched > > from using LCH to using JCH to give paint pigment colors, and I respect > > Bruce MacEvoy as an authority on giving useable values for paint > pigments: > > http://handprint.com/HP/WCL/water.html, > > http://handprint.com/LS/CVS/color.html > > > > 2. Mark Fairchild seems to think CIECAM02 is a pretty good color > apperance > > model, though again this is a field of active research, and much of what > > Mark Fairchild writes goes right over my head. > > > > 3. ArgyllCMS and LCMS already incorporate the equations for JAB/JCH in > > their code, as does RawTherapee, so it has to be not too difficult to > code > > up for GIMP. But my (very limited) efforts to make sense of the > > ArgyllCMS/LCM/RT code have so far been unsuccessful. > > > > I find the LCH blend modes, color picker, and Hue-Chroma tool to be > > incredibly useful. The few people who've written to me about using my > > patched GIMP seem very enthusiastic. > > > > JCH apparently is more accurate than LCH for describing colors. I'm not > > sure how much difference the "more accurate" would make in the digital > > darkroom. It would be nice to be able to give JCH a try, but in the > > meantime I can't imagine going back to editing without LCH. > > > > Does somebody else here know more about it? > >> > > > > No doubt even my short description above needs a lot of corrections! > > > > > > > >> Thank you in advance > >> > >> Sven > >> > >> > >> [1] > >> > >> > http://ninedegreesbelow.com/photography/high-bit-depth-gimp-tutorial-edit-tonality-color-separately.html > >> > >> > >> [2] > >> > >> > http://irtel.uni-mannheim.de/pxlab/doc/api/de/pxlab/pxl/ColorSpaceCodes.html#CS_JCh > >> > >> > >> _______________________________________________ > >> gimp-developer-list mailing list > >> List address: gimp-developer-list@xxxxxxxxx > >> List membership: > >> https://mail.gnome.org/mailman/listinfo/gimp-developer-list > >> List archives: https://mail.gnome.org/archives/gimp-developer-list > >> > >> > > _______________________________________________ > > gimp-developer-list mailing list > > List address: gimp-developer-list@xxxxxxxxx > > List membership: > > https://mail.gnome.org/mailman/listinfo/gimp-developer-list > > List archives: https://mail.gnome.org/archives/gimp-developer-list > > > > > ------------------------------ > > Message: 5 > Date: Mon, 15 Feb 2016 08:24:00 +0100 > From: ?yvind Kol?s <pippin@xxxxxxxx> > To: Elle Stone <ellestone@xxxxxxxxxxxxxxxxxxxx> > Cc: Gimp-developer <gimp-developer-list@xxxxxxxxx> > Subject: Re: Adding better LCH support to GIMP 2.10 > Message-ID: > <CAKjrkdNbdbmgz8ruVC= > b3j4qVFHObVYmQZ0E7j0f7Y11P7jw3A@xxxxxxxxxxxxxx> > Content-Type: text/plain; charset=UTF-8 > > On Mon, Feb 15, 2016 at 12:33 AM, Elle Stone > <ellestone@xxxxxxxxxxxxxxxxxxxx> wrote: > > This page briefly talks about color appearance models in more > down-to-earth > > terms: http://www.rit-mcsl.org/fairchild/WhyIsColor/Questions/4-8.html > > > > An internet search on terms like Color appearance model, Mark Fairchild, > and > > CIECAM02 will turn up a lot of material. None of it is easy reading. > > Color Appearance Models are even more in the realm of the subjective > phenomenological experience of color than CIE XYZ / CIE Lab - and less > useful in an attempt at absolutely defining/describing a color outside > the context/scene where it is experiences/observed. With a color > appearance model the squares A and B in the Checker Shadow Illusion ( > https://en.wikipedia.org/wiki/Checker_shadow_illusion ) would have > different colors - since they *appear* to have different colors. > Through color constancy this affects not only the apparent luminanace > but also the apparent hue of colors in a scene. > > /pippin > > > ------------------------------ > > Subject: Digest Footer > > _______________________________________________ > gimp-developer-list mailing list > gimp-developer-list@xxxxxxxxx > https://mail.gnome.org/mailman/listinfo/gimp-developer-list > > > ------------------------------ > > End of gimp-developer-list Digest, Vol 53, Issue 8 > ************************************************** > _______________________________________________ gimp-developer-list mailing list List address: gimp-developer-list@xxxxxxxxx List membership: https://mail.gnome.org/mailman/listinfo/gimp-developer-list List archives: https://mail.gnome.org/archives/gimp-developer-list
