March 2016 - colorsync-users

Re: Colorsync-users Digest, Vol 13, Issue 81
by Chris Cox 22 Mar '16

22 Mar '16

>I still think you owe it to yourself to examine why you're so upset at >the thought that Adobe products, which are excellent for their designed >purpose, aren't useful for a purpose they were never designed for. Except that Adobe¹s products are designed for colorimetric accuracy, and used for colorimetry rather often. Again, you are making a blanket statement based on one aspect of the products, and even that aspect is only based on your preferences, not the actual capabilities of the products. Your repeated incorrect statements are harming your reputation, and not helping anyone else on the mailing list (and may be doing damage to the understanding of others). Also, have you considered asking for better controls in ACR rather than just throwing around accusations? >>In Photoshop, if you blend in a gamma 1.0 document, > >First, that the default is anything other than gamma 1.0 blending >demonstrates that whoever wrote the code doesn't understand what gamma is >or what it's for. It's nothing more nor less than a form of data >compression, a more efficient use of the bits on the disk. No, it simply confirms that you confuse theory with practice and have little or no experience with actual practice of image processing or digital painting. >And then we've got the problem that gamma _is_ vital for the internal >storage, and forcing people to use gamma 1.0 for internal storage just to >do correct manipulation of it then opens them up to all the problems that >gamma fixes in the first place. That¹s why there has been an option to do blending in gamma 1.0 in Photoshop for many, many years (without changing the document colorspace). But, again, it really isn¹t a great idea if you are using 8 bits/channel because it will quickly lead to quantization artifacts. In 16 bit/channel gamma 1.0 blending may not be too bad, and in 32 bit/channel (floating point) it is the only option. We know how to work with gamma encodings quite well, but you are still trying to blindly apply theory to real world practice without understanding any of the issues involved. Instead of accusing people with more knowledge and experience than yourself of getting things wrong, you might want to ask WHY things are done the way they are done, so you can learn from the knowledge and experience of others. >>And you are still making broad claims based on very narrow issues (many >>of >>your own making or misunderstanding). > >Sorry, but you yourself are repeatedly pointing out the critical flaws in >Photoshop and bragging about them as if they were features, not bugs. You have not yet pointed out a flaw in Photoshop, only your own mistakes and misunderstandings (or confusing personal preference with capability). The comments about not enough precision on controls in ACR could be a feature request, but certainly not a flaw. The limited output spaces in ACR - ok, that can also be considered a feature request (although you already have minimally disturbed data in PhotoPhotoRGB). But you still seem to be going about all this in the worst possible manner. Simply asking for the features or asking for more information would help you far more than making obviously inaccurate statements on a public mailing list. Chris

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Re: Colorsync-users Digest, Vol 13, Issue 79
by Chris Cox 17 Mar '16

17 Mar '16

>>Are you pretending that the capabilities don¹t exist simply because you >>can¹t buy a commercial tool to exercise those capabilities? That is >>insane. > >The capabilities didn't even exist until about a year ago, and they're >only available in a little-known, unpolished command-line volunteer >kludge that a rather talented and dedicated (and somewhat crazy) guy >whipped up for himself to try to fix a seriously broken system and was >generous enough to share with the rest of the world. If you think that's >a meaningful answer to Adobe's inability to do colorimetric camera >input...then it's not me who's insane. So you admit that your previous claim was wrong. ACR and DNG have the capability, even if you cannot purchase the tools that you like to use those capabilities. And you have a tool that works, even if you don’t like the way it works. >>You seem to apply your misunderstandings of DNG to all Adobe products and >>operations (even those that don¹t deal with DNG or Camera Raw). > >No; those are separate problems, also show-stoppers. At least up through >non-CC versions (when I got off the crazy train), Photoshop _still_ >miserably failed many of the gamma tests that, for example, Elle Stone >has documented. As in, use a fuzzy paintbrush and Photoshop does the >fuzzy bits without bothering to reverse the profile's gamma encoding. >Maybe you can fix some of that if you know the secret magic incantation >of settings hidden behind leopard warning signs...but not all, and the >mere fact that such basic correct color handling isn't the default is >appalling. You are mixing multiple concepts, and apparently assuming that “image processing 101” theory applies in the real world (<sarcasm>because everyone knows "practice equals theory”</sarcasm>). In Photoshop, if you blend in a gamma 1.0 document, or turn on gamma 1.0 blending, then you will get gamma 1.0 blending. Of course, you may also see the artifacts that accumulate rapidly if you attempt to use gamma 1.0 blending in an 8 bit/channel document, which is why most people don’t do that unless they work in floating point (32 bit/channel) images. >Now, maybe Adobe is making enough money with CC subscriptions that it can >afford to fix some of the broken stuff. I don't know, and, frankly, I >don't care; I've long since moved on to solutions that actually work. If >so, wonderful -- and you can demonstrate that it has by spending some >time on Elle's site and putting together a bunch of demonstration images >showing that Photoshop is finally fixed. You have yet to point out anything that is actually broken. So there is nothing I can fix. >But that still doesn't address the chaos that is DNG profiling.... Again, you can’t blame the technology and app capability on your lack of preferred tools outside that app and technology. That’s like claiming that math doesn’t work because you don’t like your personal calculator. And you are still making broad claims based on very narrow issues (many of your own making or misunderstanding). You would be much better off asking about these issues instead of making easily disprovable claims that harm your reputation. Chris

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RE HOW TO GET OFF YOUR LIST
by leita luchetti 17 Mar '16

17 Mar '16

To Rick Gordon or other Person Who Might Be Able to Help, I have tried to unsubscribe from the Colorsync-users list numerous times by clicking the "unsubscribe button" on the appropriate page . All without success. If there's anything you can do to help me get LeitaLuchetti(a)gmail.com off your Colorsync-users list I would appreciate it enormously. thanks. LHL

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RE: Spectral sensivities
by Roger Breton 17 Mar '16

17 Mar '16

I have an OceanOptics USB4000 with a radiometrically calibrated tungsten light source too. Could that help? / Roger -----Original Message----- From: colorsync-users-bounces+graxx=videotron.ca(a)lists.apple.com [mailto:colorsync-users-bounces+graxx=videotron.ca@lists.apple.com] On Behalf Of Ben Goren Sent: 16 mars 2016 12:50 To: ColorSync <colorsync-users(a)lists.apple.com> Subject: Re: Spectral sensivities On Mar 16, 2016, at 9:36 AM, Wüller Dietmar <dwueller(a)gmx.de> wrote: > The easiest and cheapest way to get spectral sensitivities for a single device is to have it measured as a service. Easiest, maybe, but certainly not cheapest. And perhaps not best, either. The bill of materials for a suitable spectroscope is under $20. You'll need to know the transmission efficiency of the diffraction grating, and the least-worst way to get that is with a monochromator...but you can get a monochromator for cheap off FleaBay, and a spectroscope design can be adapted to a monochromator design if you want to continue the dirt-cheap route. And virtually nobody I'm aware of (with one notable exception who's reading these words (Hi Iliah!)) takes the lens into consideration when determining a camera's spectral sensitivities. Some lenses have rather complex spectral absorption characteristics. If you must use a lens, use Canon's "Plastic Fantastic" 50mm f/1.8; its transmission is as spectrally flat as you'll find in any lens and significantly flatter than many, including lots of top-of-the-line L glass. But if your commercial service (or whatever) assumes that the optics are spectrally flat, you've got the lens permanently "baked into" all your data. Cheers, b& _______________________________________________ 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/graxx%40videotron.ca This email sent to graxx(a)videotron.ca

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Re: Spectral sensivities
by Wüller Dietmar 16 Mar '16

16 Mar '16

> Is there a (simple) way to get at a particular camera sensors spectral sensitivities? The methods mentioned (CCSG, grating etc.) all face the calibration problem or provide a problem with the accuracy and a monochromator is everything but simple. There are a few devices like camSPECS designed for a quick and easy measurement and they are cheaper than a monochromator but not that cheap. The easiest and cheapest way to get spectral sensitivities for a single device is to have it measured as a service. Dietmar

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DNG Profile Editor question.
by Joe 16 Mar '16

16 Mar '16

Hi, everyone. I hope this message is within the range of topics with discuss here. It’s not about Colorsync but since we discuss color technology here, I thought this may be relevant and within the scope of subjects covered by the forum. I have started to use the DNG Profile Editor to create a profile for my camera + light combination. All the tutorials I've read and/or watched so far aren't clear about this aspect of the calibration or profiling process. I have used the ColorChecker Classic and ColorChecker Passport (both have the same 24 color patches). Here is the problem I am having: After I create the profile using DMG profile editor and a photo of one of the targets above, I try to read the value of the color patches but the measurements are very different from those of the patches. I thought and expected that after the profiling process the measurements I took on screen using the color samplers in ACR would display the same values as those on the color charts. For instance, the White patch has a RGB value of R-243, G-243, B-242 on the ColorChecker Classic target but when I measure my image of it on screen the values are R-246, G-245, B-244. Not a big difference here. However, the Black patch has a value of R-52, G-52, B-52 on the ColorChecker Classic target but the measurements on the screen are R-72, G-73, B-74. Just to illustrate my point: Red on target: R-175, G-54, B-60 Red on screen: R-225, G-68, B-76 Green on target: R-70, G-148, B-73 Green on screen: R-151, G-219, B-119 Blue on target: R-56, G-61, B-150 Blue on screen: R-62, G-86, B-207 Shouldn't the measurements on screen duplicate those on the target now that the camera has been profiled ? In this case what am I doing wrong and how can I improve my calibration process so my measurements on screen are accurate and reflect real life measurements ? Thank you in advance for your help.

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Re: Colorsync-users Digest, Vol 13, Issue 77
by Chris Cox 16 Mar '16

16 Mar '16

>>Please see the documentation for DNG profiles, Camera Raw, and Photoshop. > >I have. Many times. Burned many hours over it. > >And there's a trivial demonstration for why it's useless to even pretend >to attempt a colorimetric workflow with Adobe products. To the best of my >knowledge, not a single vendor sells _any_ product for building DNG >profiles with anything other than a 24-patch ColorChecker, and those >products that support a ColorChecker don't let you provide your own >measurements for the chart nor SPD information for the actual illuminant >the chart is photographed under. Are you pretending that the capabilities don¹t exist simply because you can¹t buy a commercial tool to exercise those capabilities? That is insane. Just because you cannot buy a screwdriver that you like, does not mean that the screws don¹t exist or work, or that other people don¹t have screwdrivers which they like and work for them. >Adobe makes great products for certain types of artistry. But attempting >to use Adobe products for anything where colorimetric accuracy is an >essential part of the workflow is as insane as attempting to use a >Lamborghini to sow crops or racing a farm tractor in Le Mans. You seem to apply your misunderstandings of DNG to all Adobe products and operations (even those that don¹t deal with DNG or Camera Raw). That is also more than a little insane. You may have issues with one particular method of input - but that in no way affects the rest of the applications or their capabilities. You would do far better to ask questions on this mailing list instead of making such ludicrous claims. I¹m sure that other folks on the list could help you understand your misunderstandings and mistakes. Chris

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RE: Spectral sensivities
by Roger Breton 16 Mar '16

16 Mar '16

I have an old visible range Bauch&Lomb monochromator with a 1mm exist slit. If I was to take a picture of the slit with my camera, at some reasonable interval, could that be a crude way to get to my camera's response? Hypothetically speaking. / Roger -----Original Message----- From: Iliah Borg [mailto:iliah.i.borg@gmail.com] Sent: 15 mars 2016 12:47 To: Roger Breton <graxx(a)videotron.ca> Cc: 'Ben Goren' <ben(a)trumpetpower.com>; 'ColorSync' <ColorSync-Users(a)lists.apple.com> Subject: Re: Spectral sensivities > Is there a (simple) way to get at a particular camera sensors spectral sensitivities? Simple, yes. Cheap, not so much. But sacrificing accuracy (still being within most of the practical needs), those can be restored from a shot of CC SG. Problem is, those spectral characteristics depend on temperature and heat distribution across the sensor. -- Best regards, Iliah Borg LibRaw, LLC www.libraw.org www.rawdigger.com www.fastrawviewer.com

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Re: Colorsync-users Digest, Vol 13, Issue 76
by Chris Cox 15 Mar '16

15 Mar '16

>> Adobe products are all about "pleasing" color. Colorimetric accuracy is next to impossible using Adobe products -- and DNG profiles especially. This is very much incorrect, on assumptions and fact. Please see the documentation for DNG profiles, Camera Raw, and Photoshop. Chris

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RE: Spectral sensivities
by Roger Breton 15 Mar '16

15 Mar '16

"sin 4", is that "Sinar 4"? Some kind of Sinar software, Edmund? / Roger -----Original Message----- From: colorsync-users-bounces+graxx=videotron.ca(a)lists.apple.com [mailto:colorsync-users-bounces+graxx=videotron.ca@lists.apple.com] On Behalf Of edmund ronald Sent: 15 mars 2016 14:21 To: Ben Goren <ben(a)trumpetpower.com> Cc: ColorSync <ColorSync-Users(a)lists.apple.com> Subject: Re: Spectral sensivities sin 4 On Tuesday, March 15, 2016, Ben Goren <ben(a)trumpetpower.com> wrote: > On Mar 15, 2016, at 9:39 AM, Roger Breton <graxx(a)videotron.ca > <javascript:;>> wrote: > > > Is there a (simple) way to get at a particular camera sensors > > spectral > sensitivities? > > Simplest is to get it from somebody else. > > Cheap is to build your own large-sized spectroscope, photograph a > spectrum, and combine it with various other measurements and math and > what-not. I still need to type up and post instructions and plans and > what-not. But the basic idea is that if you know the SPD reaching the > sensor (which is a product of the illuminant and the efficiencies of > everything between the illuminant and the sensor -- presumably, just > the diffraction grating and the lens) then you can treat the rainbow > image as a standard chart image to get your RGB values. Assuming the > sensor is linear (a good assumption if your capture technique is > impeccable), that's your spectral sensitivity. > > Cheers, > > b&

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