December 2022 - colorsync-users

Defeating Eye Adaptation
by Louis Dina 11 Dec '22

11 Dec '22

I would like to thank everyone for the great suggestions on how you "Defeat Eye Adaptation" when editing photos. I waited before responding to allow time for people to weigh in, so please do not think I'm not grateful for the help because I am. All of your suggestions are very helpful. I have used some of these techniques myself, but I also heard some great new ideas. I'm sometimes too lazy or impatient to take the time or make the effort, but of course that is false economy. I end up spending more time editing and reediting the same damned image! I'm sure none of you have ever been guilty of that. :o) I'm the guy who is doing woodworking and decides to skip that medium grade of sandpaper and go straight to the fine grade 'to save time'. Haha...it always takes longer that way. Anyway, thanks again. Regards, Lou

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Re: colorsync-users Digest, Vol 19, Issue 49
by Jeff Nova 07 Dec '22

07 Dec '22

I love you all. THANK YOU for being so generous with your knowledge! Happy Holidays!! : ) - Jeff Jeff Nova Chief Executive Officer Colorhythm https://colorhythm.com Mobile: +1 510-710-9590 Main: +1 415-399-9921 On Mon, Dec 5, 2022 at 12:00 PM <colorsync-users-request(a)lists.apple.com> wrote: > Send colorsync-users mailing list submissions to > colorsync-users(a)lists.apple.com > > To subscribe or unsubscribe via the World Wide Web, visit > https://lists.apple.com/mailman/listinfo/colorsync-users > or, via email, send a message with subject or body 'help' to > colorsync-users-request(a)lists.apple.com > > You can reach the person managing the list at > colorsync-users-owner(a)lists.apple.com > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of colorsync-users digest..." > > > Today's Topics: > > 1. White Balance data (Jeff Nova) > 2. Re: White Balance data (Iliah Borg) > 3. Re: White Balance data (Ben Goren) > 4. Re: White Balance data (Iliah Borg) > 5. Re: White Balance data (Ben Goren) > 6. Re: White Balance data (Iliah Borg) > 7. Re: White Balance data (Ben Goren) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Sun, 4 Dec 2022 22:22:27 -0800 > From: Jeff Nova <jnova(a)colorhythm.com> > To: colorsync-users(a)lists.apple.com > Subject: White Balance data > Message-ID: <5CA915DA-B0D0-4C97-AEF9-EDB37D79057A(a)colorhythm.com> > Content-Type: text/plain; charset=utf-8 > > I?ve run into some data where the white balance is expressed in a manner > befuddling to me: > > 1.46399. 1 1.52999 > > Is 6500K ?! There is a tint (4.2 for what that?s worth) applied to the > white balance as well, which may confound this data. > > Anyone have an idea of what these numbers might be? XYZ and xyY both seem > wrong?? > > Thanks! > Jeff > > ------------------------------ > > Message: 2 > Date: Mon, 5 Dec 2022 06:07:48 -0500 > From: Iliah Borg <iliah.i.borg(a)gmail.com> > To: colorsync-users(a)lists.apple.com > Subject: Re: White Balance data > Message-ID: <828dcbbd-2184-6cde-0d94-a100a56c1e5e(a)gmail.com> > Content-Type: text/plain; charset=UTF-8; format=flowed > > Hi Jeff, > > Those are white balance multipliers, as the cameras write them. These > multipliers equalize colour channel sensitivities > with the aim that after multiplication raw values become equal on the gray. > > The idea of expressing white balance as CCT + tint is a film paradigm, and > it is not the best for digital (not directly > measured data, difficult to calibrate, too many conversions back and > forth). > > On 12/5/22 01:22, Jeff Nova via colorsync-users wrote: > > I?ve run into some data where the white balance is expressed in a manner > befuddling to me: > > > > 1.46399. 1 1.52999 > > > > Is 6500K ?! There is a tint (4.2 for what that?s worth) applied to the > white balance as well, which may confound this data. > > > > Anyone have an idea of what these numbers might be? XYZ and xyY both > seem wrong?? > > > > Thanks! > > Jeff > > _______________________________________________ > > Do not post admin requests to the list. They will be ignored. > > colorsync-users mailing list (colorsync-users(a)lists.apple.com) > > Help/Unsubscribe/Update your Subscription: > > > https://lists.apple.com/mailman/options/colorsync-users/iliah.i.borg%40gmai… > > > > This email sent to iliah.i.borg(a)gmail.com > > -- > Best regards, > Iliah Borg > LibRaw, LLC > www.libraw.org > www.rawdigger.com > www.fastrawviewer.com > > > ------------------------------ > > Message: 3 > Date: Mon, 5 Dec 2022 07:35:31 -0700 > From: Ben Goren <ben(a)trumpetpower.com> > To: Iliah Borg <iliah.i.borg(a)gmail.com> > Cc: colorsync-users(a)lists.apple.com > Subject: Re: White Balance data > Message-ID: <7BA560F8-8884-4FA8-BC27-DBB571E35930(a)trumpetpower.com> > Content-Type: text/plain; charset=utf-8 > > Just to elaborate a bit, they?re linear multipliers meant to be applied to > the raw data recorded by the camera. Take every red pixel, multiply it by > 1.46399. Leave the green pixels as they are. > > They?ll be very specific to the camera model. The spectral sensitivity of > a Canon 5DII is very similar to, but not identical to, that of a Canon > 5DIII. > > And, of course, they correspond to the reference illuminant. You mention > that this is for 6500K; the values would be different (but very close) for > 6501K, for D65, for an actual illuminant with a measured CCT of 6500K, and > for an actual illuminant with a measured CCT of 6500K in non-neutral > surroundings. > > If you have a photo of a reference chart (a 24-patch ColorChecker is > perfect), you can easily determine the exact figures for that scene. Use > the raw developer to dump the linear raw data ? no exposure, no gamma, no > white balance, no nothing except demosaicing. Create an ICC profile from > the chart and ask the chart what RGB values correspond with L*=100, a*=0, > b*=0; this will be a reverse lookup. Basic high school algebra will tell > you what multipliers you need to make that value be R=100%, G=100%, B=100%. > This will, incidentally, also give you the perfect exposure adjustment. > > Note that most people who have little to no experience shooting raw > inevitably wind up underexposing their images, often dramatically so. > Digital cameras have an overabundance of dynamic range, so the raw > converters have no trouble silently and automatically covering up the > underexposure. But don?t be surprised if your image of the ColorChecker is > so dark that you can?t even find where the chart is on the image. In that > case, if at all possible, adjust your exposure accordingly and re-shoot the > scene. > > Iliah?s RawDigger analysis software is an essential tool for anybody doing > serious raw photography, and the Web site for RawDigger is possibly the > best guide to raw exposure techniques (and related subjects) you?ll find > anywhere. If you?re going to do anything like what I described above, > you?ll want to use RawDigger to extract the values from the ColorChecker to > create a GCATS file that you?d hand to your ICC profiler. There are other > ways to do that sort of thing ? but ? > > Cheers, > > b& > > > On Dec 5, 2022, at 4:07 AM, Iliah Borg via colorsync-users < > colorsync-users(a)lists.apple.com> wrote: > > > > Hi Jeff, > > > > Those are white balance multipliers, as the cameras write them. These > multipliers equalize colour channel sensitivities with the aim that after > multiplication raw values become equal on the gray. > > > > The idea of expressing white balance as CCT + tint is a film paradigm, > and it is not the best for digital (not directly measured data, difficult > to calibrate, too many conversions back and forth). > > > > On 12/5/22 01:22, Jeff Nova via colorsync-users wrote: > >> I?ve run into some data where the white balance is expressed in a > manner befuddling to me: > >> 1.46399. 1 1.52999 > >> Is 6500K ?! There is a tint (4.2 for what that?s worth) applied to the > white balance as well, which may confound this data. > >> Anyone have an idea of what these numbers might be? XYZ and xyY both > seem wrong?? > >> Thanks! > >> Jeff > >> _______________________________________________ > >> Do not post admin requests to the list. They will be ignored. > >> colorsync-users mailing list (colorsync-users(a)lists.apple.com) > >> Help/Unsubscribe/Update your Subscription: > >> > https://lists.apple.com/mailman/options/colorsync-users/iliah.i.borg%40gmai… > >> This email sent to iliah.i.borg(a)gmail.com > > > > -- > > Best regards, > > Iliah Borg > > LibRaw, LLC > > www.libraw.org > > www.rawdigger.com > > www.fastrawviewer.com > > _______________________________________________ > > Do not post admin requests to the list. They will be ignored. > > colorsync-users mailing list (colorsync-users(a)lists.apple.com) > > Help/Unsubscribe/Update your Subscription: > > > https://lists.apple.com/mailman/options/colorsync-users/ben%40trumpetpower.… > > > > This email sent to ben(a)trumpetpower.com > > > > ------------------------------ > > Message: 4 > Date: Mon, 5 Dec 2022 11:36:35 -0500 > From: Iliah Borg <iliah.i.borg(a)gmail.com> > To: Ben Goren <ben(a)trumpetpower.com> > Cc: colorsync-users(a)lists.apple.com > Subject: Re: White Balance data > Message-ID: <136a1dd1-2001-a558-d918-8940dd72c212(a)gmail.com> > Content-Type: text/plain; charset=UTF-8; format=flowed > > Hi Ben, > > > They?ll be very specific to the camera model. > > In Canon's case, they will be specific to individual camera sample, too > (sometimes they even vary with the sensor > temperature); and the table is stored in raw files. > > > -- > Best regards, > Iliah Borg > LibRaw, LLC > www.libraw.org > www.rawdigger.com > www.fastrawviewer.com > > > ------------------------------ > > Message: 5 > Date: Mon, 5 Dec 2022 09:41:10 -0700 > From: Ben Goren <ben(a)trumpetpower.com> > To: Iliah Borg <iliah.i.borg(a)gmail.com> > Cc: colorsync-users(a)lists.apple.com > Subject: Re: White Balance data > Message-ID: <B32F253A-2030-41A7-B327-6908754B47E8(a)trumpetpower.com> > Content-Type: text/plain; charset=utf-8 > > I was actually thinking of asking about that ? but not variation with > respect to sensor temperature but rather with age. > > Has anybody done any recent measurements of years-old cameras to see how > much they?re changing? I mean, of course they?re changing; entropy is > inescapable. But are the changes measurable, and significant if so? Any > guidelines on how often one might need to re-profile a device? > > b& > > > On Dec 5, 2022, at 9:36 AM, Iliah Borg <iliah.i.borg(a)gmail.com> wrote: > > > > Hi Ben, > > > > > They?ll be very specific to the camera model. > > > > In Canon's case, they will be specific to individual camera sample, too > (sometimes they even vary with the sensor temperature); and the table is > stored in raw files. > > > > > > -- > > Best regards, > > Iliah Borg > > LibRaw, LLC > > www.libraw.org > > www.rawdigger.com > > www.fastrawviewer.com > > > > ------------------------------ > > Message: 6 > Date: Mon, 5 Dec 2022 12:32:48 -0500 > From: Iliah Borg <iliah.i.borg(a)gmail.com> > To: Ben Goren <ben(a)trumpetpower.com> > Cc: colorsync-users(a)lists.apple.com > Subject: Re: White Balance data > Message-ID: <50d5a009-06ff-5c20-1ef6-c0ba9fa85bdf(a)gmail.com> > Content-Type: text/plain; charset=UTF-8; format=flowed > > Dear Ben, > > OK, re-measured my Oly E-P2 (the oldest one I kept measurements from) > after giving it a thorough sensor cleaning. Over > 512 by 512 center region the measurements are the same as they were. 64 by > 64 region - 0.2% difference between today's > and May, 2010. > > > On 12/5/22 11:41, Ben Goren wrote: > > I was actually thinking of asking about that ? but not variation with > respect to sensor temperature but rather with age. > > > > Has anybody done any recent measurements of years-old cameras to see how > much they?re changing? I mean, of course they?re changing; entropy is > inescapable. But are the changes measurable, and significant if so? Any > guidelines on how often one might need to re-profile a device? > > > > b& > > > >> On Dec 5, 2022, at 9:36 AM, Iliah Borg <iliah.i.borg(a)gmail.com> wrote: > >> > >> Hi Ben, > >> > >>> They?ll be very specific to the camera model. > >> > >> In Canon's case, they will be specific to individual camera sample, too > (sometimes they even vary with the sensor temperature); and the table is > stored in raw files. > >> > >> > >> -- > >> Best regards, > >> Iliah Borg > >> LibRaw, LLC > >> www.libraw.org > >> www.rawdigger.com > >> www.fastrawviewer.com > > > > -- > Best regards, > Iliah Borg > LibRaw, LLC > www.libraw.org > www.rawdigger.com > www.fastrawviewer.com > > > ------------------------------ > > Message: 7 > Date: Mon, 5 Dec 2022 10:40:09 -0700 > From: Ben Goren <ben(a)trumpetpower.com> > To: Iliah Borg <iliah.i.borg(a)gmail.com> > Cc: colorsync-users(a)lists.apple.com > Subject: Re: White Balance data > Message-ID: <AC90AAB9-0E60-415C-A82C-2A3A3E123C52(a)trumpetpower.com> > Content-Type: text/plain; charset=utf-8 > > Thanks ? that?s good to know! That kind of stability is impressive and > reassuring ? and I wouldn?t even be surprised if it?s within the margin of > error of your measurement system. > > My guess is that the CMOS / CCD arrays should be exceptionally stable; my > biggest concern is the stability of the color filters. But the mirror box > of a camera is almost always effectively as dark as dark gets in the > everyday world ? if the color filters are as stable as, say, the pigments > used for archival prints, then something else will kill the camera before > color accuracy suffers. > > b& > > > On Dec 5, 2022, at 10:32 AM, Iliah Borg <iliah.i.borg(a)gmail.com> wrote: > > > > Dear Ben, > > > > OK, re-measured my Oly E-P2 (the oldest one I kept measurements from) > after giving it a thorough sensor cleaning. Over 512 by 512 center region > the measurements are the same as they were. 64 by 64 region - 0.2% > difference between today's and May, 2010. > > > > > > On 12/5/22 11:41, Ben Goren wrote: > >> I was actually thinking of asking about that ? but not variation with > respect to sensor temperature but rather with age. > >> Has anybody done any recent measurements of years-old cameras to see > how much they?re changing? I mean, of course they?re changing; entropy is > inescapable. But are the changes measurable, and significant if so? Any > guidelines on how often one might need to re-profile a device? > >> b& > >>> On Dec 5, 2022, at 9:36 AM, Iliah Borg <iliah.i.borg(a)gmail.com> wrote: > >>> > >>> Hi Ben, > >>> > >>>> They?ll be very specific to the camera model. > >>> > >>> In Canon's case, they will be specific to individual camera sample, > too (sometimes they even vary with the sensor temperature); and the table > is stored in raw files. > >>> > >>> > >>> -- > >>> Best regards, > >>> Iliah Borg > >>> LibRaw, LLC > >>> www.libraw.org > >>> www.rawdigger.com > >>> www.fastrawviewer.com > > > > -- > > Best regards, > > Iliah Borg > > LibRaw, LLC > > www.libraw.org <http://www.libraw.org/> > > www.rawdigger.com <http://www.rawdigger.com/> > > www.fastrawviewer.com <http://www.fastrawviewer.com/> > > > ------------------------------ > > Subject: Digest Footer > > _______________________________________________ > colorsync-users mailing list > colorsync-users(a)lists.apple.com > https://lists.apple.com/mailman/listinfo/colorsync-users > > > ------------------------------ > > End of colorsync-users Digest, Vol 19, Issue 49 > *********************************************** >

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Electronic Imaging Symposium (EI 2023): Program Announced, Register by 25 DEC!
by Roberta Morehouse 07 Dec '22

07 Dec '22

The Electronic Imaging Symposium (EI 2023) is back in person! 15-19 January 2023, San Francisco, CA https://bit.ly/EI2023 Explore all facets of electronic imaging research and innovation-human perception and cognition, AR/VR, computational imaging, autonomous vehicles, computational display, high-performance computing-and more during EI 2023. SHORT COURSE PROGRAM Deep Dive + Learn New Skills Twenty-two (22) courses taught by academic and industry experts provide participants with a deeper understanding and an opportunity to explore new areas in topics that range from 3D and AR/VR to machine vision, deep learning, and more. Save 10% off 3+ classes. https://bit.ly/EI2023_Courses PLENARY TALKS (more to come) EI speakers are leaders who educate and inspire by pushing the limits and challenging what we know. * Anima Anandkumar, Bren professor, California Institute of Technology, and senior director of AI Research, NVIDIA Corporation * Andrew B. Watson, chief vision scientist, Apple Inc. https://bit.ly/EI2023_Plenaries CONFERENCE PROGRAMS Eighteen (18) conferences that feature keynote and invited talks, oral & poster presentations, best paper awards, and networking + social events. New for 2023: High-Performance Computing for Imaging 2023 (HPCI) https://bit.ly/EI2023_Conferences Learn more and register by 25 December for savings- rates increase on 12/26. https://bit.ly/EI2023 Roberta Morehouse, CMP Communications and Marketing Manager Society for Imaging Science and Technology (IS&T) -imaging across applications- IS&T is a non-profit organization dedicated to advancing science and technology in the field of imaging. Please consider donating<https://www.imaging.org/site/IST/About_Us/Donations/IST/About/Donations.asp…> today. Connect with us on LinkedIn<https://www.linkedin.com/company/society-for-imaging-science-and-technology…> and Twitter<https://twitter.com/ImagingOrg> @ImagingOrg

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Defeating Eye Adaptation
by Louis Dina 07 Dec '22

07 Dec '22

I'm curious how others deal with "Eye Adaptation" when editing images. The longer we stare at the monitor, the more "normal" the image appears. Our eyes adjust and often fool us, at least they do me. It may be too bright, dark, contrasty, flat, over or undersaturated, etc. Sometimes I think the image looks great, but when I come back after 5 minutes, obvious needed changes scream out at me. So, what do you do to defeat eye adaptation? Thanks, Lou

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White Balance data
by Jeff Nova 05 Dec '22

05 Dec '22

I’ve run into some data where the white balance is expressed in a manner befuddling to me: 1.46399. 1 1.52999 Is 6500K ?! There is a tint (4.2 for what that’s worth) applied to the white balance as well, which may confound this data. Anyone have an idea of what these numbers might be? XYZ and xyY both seem wrong…? Thanks! Jeff

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