Luminous Landscape Forum
Raw & Post Processing, Printing => Colour Management => Topic started by: Hermie on September 15, 2009, 03:32:09 am
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http://www.xrite.com/company_press_room.aspx?News=594 (http://www.xrite.com/company_press_room.aspx?News=594)
http://www.xrite.com/product_overview.aspx?ID=1257 (http://www.xrite.com/product_overview.aspx?ID=1257)
http://www.outbackphoto.com/CONTENT_2007_0...port/index.html (http://www.outbackphoto.com/CONTENT_2007_01/section_workflow_basics_2009/20090915_ColorCheckerPassport/index.html)
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Interesting. I'm not sure it offers me much more than using my existing color checker and Adobe's DNG profile editor, but maybe there's more in the detail.
Nice to see a realistic price point too.
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http://www.xrite.com/company_press_room.aspx?News=594 (http://www.xrite.com/company_press_room.aspx?News=594)
http://www.xrite.com/product_overview.aspx?ID=1257 (http://www.xrite.com/product_overview.aspx?ID=1257)
http://www.outbackphoto.com/CONTENT_2007_0...port/index.html (http://www.outbackphoto.com/CONTENT_2007_01/section_workflow_basics_2009/20090915_ColorCheckerPassport/index.html)
Really cool - it wasn't convinient to put the old CC24 into photo bag, and the mini version was too small and only good for macro purposes.
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the mini version was too small
Not my experience. So small it takes up very little room in the camera bag, so is always with me, and can be held at arms length and a sample shot easily taken with everything except long zooms and telephotos.
Also cheap enough not worry too much about the risk of loss or damage.
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Not my experience. So small it takes up very little room in the camera bag, so is always with me, and can be held at arms length and a sample shot easily taken with everything except long zooms and telephotos.
Also cheap enough not worry too much about the risk of loss or damage.
So or so the new CC Passport looks nice. It's a shame that the software looks rather disappointing - it only makes camera profiles, the DNG Profile Editor is much more complex.
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This isn't what Eric Chan was referring to in a previous post (http://luminous-landscape.com/forum/index.php?s=&showtopic=31074&view=findpost&p=251361) is it? This product doesn't seem to show the guts of what's going on under the hood at all.
On the other hand the DNG profile editor must always start from a base profile. There is nothing preventing someone from using this passport product to generate a new profile and subsequently tweak it in the DNG profile editor, right?
Sean
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I fully intend to do just that and retire my mini checker (which works fine thank you with the DNG Profile Editor) that has been making custom profiles at weddings for me since the DNG Profile Editor was released pretty much.
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the Passport software has been posted.
http://www.xrite.com/product_overview.aspx...;SoftwareID=917 (http://www.xrite.com/product_overview.aspx?ID=1257&Action=support&SoftwareID=917)
It's a 181MB download. WTF? Seems, um, bloated.
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The new Passport looks great, from a size and convenience standpoint. I'm wondering, though, if it uses a different process or yields any different results than one would get from using a standard ColorChecker and DNG Profile Editor. Is the profiling software the same, under the hood?
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the Passport software has been posted.
http://www.xrite.com/product_overview.aspx...;SoftwareID=917 (http://www.xrite.com/product_overview.aspx?ID=1257&Action=support&SoftwareID=917)
It's a 181MB download. WTF? Seems, um, bloated.
So I guess there's nothing to stop people from using this software to create profiles using one of the other color checker's. I wonder how it compares to the DNG Profiler.
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So I guess there's nothing to stop people from using this software to create profiles using one of the other color checker's. I wonder how it compares to the DNG Profiler.
Seems to be the case. I've just downloaded and installed it and tried it out on a couple of images. The workflow with Lightroom is certainly better than using Adobe's own editor, but......
My initial impression is that the results are inferior to using the Adobe DNG editor, giving rather over saturated reds and purples. Although different cameras may give different results.
I'll stick to the Adobe product then. Although I'd buy the passport set for it's neat color checker if I ever needed to replace my current mini color checkers.
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This is indeed one of the tools to which I was referring.
To answer some questions asked in this thread:
Correct, you can certainly create a profile with X-Rite's Passport software, then tweak it in Adobe's DNG Profile Editor if you wish. Tutorial 3 on the DNG PE page explains how to do this: http://labs.adobe.com/wiki/index.php/DNG_P...l_base_profiles (http://labs.adobe.com/wiki/index.php/DNG_Profiles:Editor#tutorial_base_profiles)
No, Adobe's DNG Profile Editor and X-Rite's Passport software do not share the same automated profile-building technology under the hood. The profile-building methods were developed separately and independently. Hence you can expect that profiles built from the same measurement data (i.e., from a single chart shot, or pair of chart shots) from the two software programs will differ somewhat. Similar to how you can measure a printer profile target, obtaining a single set of measurement data, but produce rather different printer profiles by using different software (e.g., ProfileMaker vs MonacoPROFILER).
Due to technical limitations, camera profiles are necessarily imperfect, and hence each software must make tradeoffs in terms of which color characteristics it is optimizing for. Since different software programs tend to optimize for different things, it is natural that the resulting profiles will also behave somewhat differently.
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the Passport software has been posted.
http://www.xrite.com/product_overview.aspx...;SoftwareID=917 (http://www.xrite.com/product_overview.aspx?ID=1257&Action=support&SoftwareID=917)
It's a 181MB download. WTF? Seems, um, bloated.
Your link is no longer valid.
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LOL
Looks like they didn't intend to be giving it away to those without the new color checker. I guess those who were able to download it before they put it behind a login page slipped under the radar.
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Hence you can expect that profiles built from the same measurement data (i.e., from a single chart shot, or pair of chart shots) from the two software programs will differ somewhat.
They do. In the testing I did with the 5DMII, I preferred the X-Rite profiles but the differences were pretty subtle. What’s really nice is the ability to do this all within LR. Now if I could get that app to update new profiles without quitting (which old versions of Photoshop had as well), that be cool. Its too bad X-Rite didn’t provide an editor and yes, its nice you can still use Adobe’s.
The off colored white squares are also somewhat useful in some cases where you’d rather just keep clicking on a patch with the WB tool instead of messing with tint/temp slider but either will work.
I did zero testing in building ICC profiles for obvious reasons to some <g>.
The best thing about the product is having all those targets together in a small and protected container. If you’ve got a Macbeth and want DNG profiles, there’s a free solution thanks to Adobe. Otherwise, the product is really buying you some targets.
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The best thing about the product is having all those targets together in a small and protected container. If you’ve got a Macbeth and want DNG profiles, there’s a free solution thanks to Adobe. Otherwise, the product is really buying you some targets.
Heck yeah! a lot better than getting my assistant to do the same thing in the past but without the convenience, oh and trying to hold that mini checker without finger tip shadows on the colour squares, or stopping a very expensive piece of card from dying at the edges (like mine had). I'm probably going to carry on using DNG Profile Converter, I use ACR not LR but for the convenience it's worth it for me, far easier to tell a bride to hold the case than do what my assistant is doing below! Expecting my passport by the end of this week and I've already sold the old chart to a friend who may actually pay me one day...
(http://www.studio-beni.net/whibal.jpg)
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I've tried to create a camera profile for my D3 using the ColorChecker Mini and I get an error message in DNG Profile Editor, saying "Unable to set white balance using gray patches. Please use the four color circles to identify the four corner patches of the chart and try again."
Could I be getting this error message because the Mini has larger borders around the targets?
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Could I be getting this error message because the Mini has larger borders around the targets?
Shouldn’t be the case. It sounds like either its having issues identifying the four corners or the WB is way off.
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Hi Andrew,
How are things? I spoke with you at ProPhoto and I'm now trying to create camera profiles using the flash units I have and the ColorChecker Mini. I ETTR when shooting the Mini and then turned down the Exp to -.83 to bring the White Target back to white with texture 97%/97%/97% (wasn't sure what percentage was equivalent to 255/255/255).
No matter whether I reposition the circles or not, I still get the error message I posted before. I also tried turning down the exposure some more, as well as up and still get the error message in the DNG PE. Not sure what I'm doing wrong.
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I ETTR when shooting the Mini and then turned down the Exp to -.83 to bring the White Target back to white with texture 97%/97%/97% (wasn't sure what percentage was equivalent to 255/255/255).
No matter whether I reposition the circles or not, I still get the error message I posted before. I also tried turning down the exposure some more, as well as up and still get the error message in the DNG PE. Not sure what I'm doing wrong.
100% would be 255 (more or less).
Also, I see some purple hook goodies next to the patches and that might be the issue. The software may be expecting black.
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Hi Joseph, if you send me the file I can take a look and see what's going wrong. If the file is large, try YouSendIt.com with a target email address of madmanchan2000@yahoo.com.
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100% would be 255 (more or less).
Also, I see some purple hook goodies next to the patches and that might be the issue. The software may be expecting black.
Oh, OK, I'll give that a try (removing the hooks) and put something behind the Mini to hold it up. I did try using the X-Rite Passport software and it was able to recognize every target, but couldn't build a profile because it said that at least one channel was clipped, probably due to overexposure. Could that be happening with the DNG PE as well? That means ETTR and exp to the right can't work, despite being able to bring the exposure back under clipping.
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That means ETTR and exp to the right can't work, despite being able to bring the exposure back under clipping.
You probably do want to back off on the exposure and see how it flies and no, you’re not pigeon holed into shooting the target and using the subsequent profile with the identical exposure settings. Eric might be able to explain why (I suspect due to the processing order of the use of the profile and that of the Exposure slider).
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Yes, overexposure is most likely the issue here. You generally do not want to be too aggressive with ETTR when doing the color work. As long as you're shooting at low ISO and do not hideously underexpose the image, noise should not affect the color profile quality.
Basically, when a channel is clipped, it becomes very unreliable for the purposes of color estimation (at least, for building a profile). Obviously for natural images you can sometimes get away with it, with various highlight recovery tools, but that's not good for profile building.
Quite frankly most of the time when I'm shooting profile targets I just use the evaluative/matrix metering in Av mode ...
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Yes, overexposure is most likely the issue here. You generally do not want to be too aggressive with ETTR when doing the color work. As long as you're shooting at low ISO and do not hideously underexpose the image, noise should not affect the color profile quality.
Basically, when a channel is clipped, it becomes very unreliable for the purposes of color estimation (at least, for building a profile). Obviously for natural images you can sometimes get away with it, with various highlight recovery tools, but that's not good for profile building.
It sounds like ETTR, useful for reducing noise in shadows isn’t necessary for the capture of the target and anything close to over exposure, certainly any channel clipping, causes issues with profile generation.
I guess an interesting experiment would be, bracketing the capture of the target without clipping and building a group of profiles. But based on what you say above, would it be fair to say, the net results would be the same quality profile?
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I've now been using the Passport device for a while, and have found that the extra convenience of the hard case means I actually remember to chuck it in my bag more often :-)
I've had the appropriate gear for ICC profiling for some years, but rarely ever needed it for my work - I know it's of use in some situations, but all too often it's more trouble than it's worth (YMMV)
The DNG profiles I've done for a few jobs have definitely improved the balance of colours under some fluorescent lighting, but I should emphasise that I'm not often doing colour critical work - Looking good normally trumps absolute accuracy ;-)
Some more 'Passport' observations: ColorChecker Passport review (http://www.northlight-images.co.uk/reviews/photography/colorchecker-passport_1.html)
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The advantages for the PassPort are many and many yet to be discovered.
Each type of photography will benefit in different ways.
I have and continue to do studio tethered shooting directly into LR. In the past I made camera calibrations via Bruce Fraser and Eric Chan's instructions which built a sometimes accurate profile but was not reliable for varying light only the light the camera calibration was made in.
The Passport makes a usable reliable profile that works in many lighting situations , even multiple ISO ratings.
The Dual illuminate goes much further in building a multi environment profile for mixed lighting.
In studio the raw colours based on the Passport profile are the best starting point, as Canon defaults are not accurate or precise, never have been, until now with the Passport.
Yet , you see , the base profile from Passport is the key, then you add lights, filters whatever you want , and the base camera profile is the best starting point. Easy to use, extremely helpful , a must have for any image producers already on top of their CM system.
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I was able to create several camera profiles (diff't studio lights & modifiers) for my studio shots of antiquities in the last several weeks, thanks to the generous help of Andrew and Eric, .... although I still found the necessity to WB despite having created and used a custom camera profile confusing.
In any case, I took several shots and the resulting color was already good with the standard profiles. I then applied the custom profile and the image got a little darker and slightly more contrasty. I still had to adjust the tint ever so slightly to get more of the green that I was seeing in the object under almost all lighting conditions, but failed to appear under studio lighting conditions. I'm not sure if this is a result of an optical effect (physical interaction of studio lights partially transmitting thru translucent object) or something else. Perhaps we need to purchase an Eizo CG301W.
Thanks to all for the help!
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I've now been using the Passport device for a while, and have found that the extra convenience of the hard case means I actually remember to chuck it in my bag more often :-)
Yes, I consulted for Xrite on the photographic aspects of this product, and I stressed the importance of robust packaging and in-use protection for a tool that needs to be taken to location and used there.
Edmund
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I am disappointed with ColorChecker Passport (CCP) in particular and DNG-profiling in general. I've tested CCP aganst ProfileMaker for various lighting conditions (D50, D65, A, mixed). This program has nothing with color accuracy. Color differences between CCP values and values measured by i1Pro (and taking into account the effect of metamerism for non D50 lighting conditions) sometimes exceeded 25 deltaE [76] for ColorChecker patches. (Color differences for ProfileMaker did not exceed 2-3 deltaE). And CCP has no settings at all.
By the way, what is the purpose of the file "ColorChecker24_spectral.txt" in CCP directory "win\Reference"? I thought that it was the reference. But it is NOT used by CCP.
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I am disappointed with ColorChecker Passport (CCP) in particular and DNG-profiling in general. I've tested CCP aganst ProfileMaker for various lighting conditions (D50, D65, A, mixed). This program has nothing with color accuracy. Color differences between CCP values and values measured by i1Pro (and taking into account the effect of metamerism for non D50 lighting conditions) sometimes exceeded 25 deltaE [76] for ColorChecker patches. (Color differences for ProfileMaker did not exceed 2-3 deltaE). And CCP has no settings at all.
By the way, what is the purpose of the file "ColorChecker24_spectral.txt" in CCP directory "win\Reference"? I thought that it was the reference. But it is NOT used by CCP.
That is a large difference.
Not sure I follow the procedure though.
The new chart is made to have a quite uniform spectral response so I can't see the point in having controls for bias of a presumed amount of variance in distribution from D50????
The idea is shoot the chart in the light you are capturing , the response of the captor to the scene or chart in this case have to include the spectral differences. In theory that DNG profile then should place the values so that correct metamerism is reflected in the output of the source colours to working space.
It's obvious it isn't working for you. I would like to find out more. As many are trying on different cameras, systems etc there may be times when it doesn't work. Perhaps you are one instance.
It is working fine on my Canon 5DMKII against any colours I have been shooting and testing visually. I am not going to try to analyse numerically what I don't need to as if the colours repro'd for me are what are sitting in front of me, it does what it should , for me, and my gear.
What I did when I first got it was place the Passport on different copy work, prints, different media, different light, and then built profiles. In each case the colours came in far more precise than using the stock profiles. Again , I know the contrast is boosted, and certain colours are too saturated, but others are so much better than the stock LR profiles.
I only have one Dslr, so I can't test others just yet.
That is why I am very interested in your set up, why it's not working. How many users is it working for , how many not so well, and how many not at all. Delta 25 is for me a too large of error, but again compared to what exactly?
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I know the contrast is boosted, and certain colours are too saturated, but others are so much better than the stock LR profiles.
I only have one Dslr, so I can't test others just yet.
That is why I am very interested in your set up, why it's not working. How many users is it working for , how many not so well, and how many not at all. Delta 25 is for me a too large of error, but again compared to what exactly?
I got the effect of excessively saturated colors and contrast too (D3x, Tungsten), with the Passport software. This is definitely an issue.
I'll be delighted to meet up with you, Neil, if you wan to test more cameras.
Edmund
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neil snape
I own Canon 5D mark II and 40D only. I used an Eye-One Pro UV-cut spectrophotometer, standard X-Rite ColorChecker target and X-Rite/GretagMacbeth ProfileMaker v.5.0.8.
First I measured my X-Rite ColorChecker with i1Pro UV-cut and KeyWizard software.
D50 example
1. For shooting I used sunlight with D50 lighting condition. CRI was 97 (i1Pro and i1Share software were used).
2. The ColorChecker target was shooted as recomended. Then I built DNG profile in CCP software and got the image in ACR plugin.
3. ColorChecker patches of the image were measured in Photoshop v.10.0.1.
4. Differences between these values and true values were calculated.
Results are here.
Colors were oversaturated. The same was for D65, A and mixed lighting conditions.
BTW Adobe DNG Profile Editor is not better.
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neil snape
I own Canon 5D mark II and 40D only. I used an Eye-One Pro UV-cut spectrophotometer, standard X-Rite ColorChecker target and X-Rite/GretagMacbeth ProfileMaker v.5.0.8.
First I measured my X-Rite ColorChecker with i1Pro UV-cut and KeyWizard software.
D50 example
1. For shooting I used sunlight with D50 lighting condition. CRI was 97 (i1Pro and i1Share software were used).
2. The ColorChecker target was shooted as recomended. Then I built DNG profile in CCP software and got the image in ACR plugin.
3. ColorChecker patches of the image were measured in Photoshop v.10.0.1.
4. Differences between these values and true values were calculated.
Results are here.
Colors were oversaturated. The same was for D65, A and mixed lighting conditions.
BTW Adobe DNG Profile Editor is not better.
And what if you shoot a repro chart and print it. Compare it under normalised lighting. Does it really come out to your eye at >25dE?
If it does that would back up the measured values.
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neil snape
I own Canon 5D mark II and 40D only. I used an Eye-One Pro UV-cut spectrophotometer, standard X-Rite ColorChecker target and X-Rite/GretagMacbeth ProfileMaker v.5.0.8.
First I measured my X-Rite ColorChecker with i1Pro UV-cut and KeyWizard software.
D50 example
1. For shooting I used sunlight with D50 lighting condition. CRI was 97 (i1Pro and i1Share software were used).
2. The ColorChecker target was shooted as recomended. Then I built DNG profile in CCP software and got the image in ACR plugin.
3. ColorChecker patches of the image were measured in Photoshop v.10.0.1.
4. Differences between these values and true values were calculated.
Results are here.
Colors were oversaturated. The same was for D65, A and mixed lighting conditions.
BTW Adobe DNG Profile Editor is not better.
Your results are impressive. I posted some results (http://luminous-landscape.com/forum/index.php?s=&showtopic=39083&view=findpost&p=324632)earlier, also showing that the Passport and Adobe DNG editor profiles boost saturation. I think that this may be intentional, since many users prefer saturated colors. Delta E is a standard for color errors, but it may not be the best way to compare profiles, since it involves luminance and small changes in exposure may affect the results. Also, a change is hue is more objectionable than a change in chroma (saturation), and the latter is actually preferred in some instances. I think the way Imatest (http://www.imatest.com/docs/colorcheck_ref.html) color check reports the results is preferable.
Bill
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Your results are impressive. I posted some results (http://luminous-landscape.com/forum/index.php?s=&showtopic=39083&view=findpost&p=324632)earlier, also showing that the Passport and Adobe DNG editor profiles boost saturation. I think that this may be intentional, since many users prefer saturated colors. Delta E is a standard for color errors, but it may not be the best way to compare profiles, since it involves luminance and small changes in exposure may affect the results. Also, a change is hue is more objectionable than a change in chroma (saturation), and the latter is actually preferred in some instances. I think the way Imatest (http://www.imatest.com/docs/colorcheck_ref.html) color check reports the results is preferable.
Bill
Thanks for your comment and the links.
Yes, you are right: people like saturated colors
When I need to get accurate colors on an image, I build ICC input profile. In this case color errors are minimal.
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If you are trying to measure output-referred values (e.g., in Photoshop) and compare them to published reference values, they will likely be far off. In general the auto profiles created by the DNG Profile Editor and X-Rite software do not adjust the tone curve. Therefore, using these profiles within CR/LR will result in using the default tone curve within CR/LR, which has a fair amount of brightening and contrast added. Also the Blacks setting of 5 (default value in CR/LR) will step on the shadows a bit and also result in punched up colors. You can use a linearized tone curve within CR/LR by setting Brightness, Contrast, and Blacks to zero, and setting Point Curve to linear. You can then adjust Exposure so that the gray values match up reasonably well with the published chart values, assuming reasonably uniform illumination on the chart. The result will be closer to published values, but if you try to use these settings on real images, they will not look so good ...
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madmanchan
Thank you very much for the clarification.
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If you are trying to measure output-referred values (e.g., in Photoshop) and compare them to published reference values, they will likely be far off. In general the auto profiles created by the DNG Profile Editor and X-Rite software do not adjust the tone curve. Therefore, using these profiles within CR/LR will result in using the default tone curve within CR/LR, which has a fair amount of brightening and contrast added. Also the Blacks setting of 5 (default value in CR/LR) will step on the shadows a bit and also result in punched up colors. You can use a linearized tone curve within CR/LR by setting Brightness, Contrast, and Blacks to zero, and setting Point Curve to linear. You can then adjust Exposure so that the gray values match up reasonably well with the published chart values, assuming reasonably uniform illumination on the chart. The result will be closer to published values, but if you try to use these settings on real images, they will not look so good ...
Thanks Eric.
You always say things much clearer than I ever could.
What you say is what I was thinking, and clearly describes the reasons for such discrepancies.
I didn't really understand the comparison procedure which resulted in the large dE differences and as I had asked what was done to get from A to B>
I do think it is going to continue to be a repeating question of scene recording passing through to working space via a camera calibration or base set up being called a profile. To add to that confusion the beta version even had an ICC camera profile export which is quite a bit different than a DNG, or camera calibration *profile*.
Problem with black clipping in LR/CR is with the profiles created they are saturating some colours more than others. By backing off the default black clip from 5 to less the colours that are saturated , yes they becomes less saturated but so do the colours that are close to being where they should be.
Is it possible to use the DNG editor to tweak the PassPort profiles?
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Is it possible to use the DNG editor to tweak the PassPort profiles?
I alredy tried it - and it works.
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I find it hilarious that people are complaining about lack of "color accuracy" and using non-linear tone curves, etc. Clipping blacks to boost contrast is a valid creative image adjustment, but it has nothing to do with accuracy. The same is true of using S-curves to boost contrast. If you want "accurate" colors, all of the "creative" adjustments have to be TURNED OFF.
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I find it hilarious that people are complaining about lack of "color accuracy" and using non-linear tone curves, etc. Clipping blacks to boost contrast is a valid creative image adjustment, but it has nothing to do with accuracy. The same is true of using S-curves to boost contrast. If you want "accurate" colors, all of the "creative" adjustments have to be TURNED OFF.
You are absolutely right. There will be a lot of confusion by the naming involved and the comprehension of what the expected colours will be.
I think it is used to correlate what the camera sees as a base into LR/CR. What controls you apply in LR/CR to the raw files certainly do affect the balance. That said if you look at the passport profiles there will be certain colours with certain cameras that will have an exaggerated saturation in some areas, which may or may not be to your liking. For me it's okay as I am not counting on accuracy for scene rendering to working space, rather a nice balance close to what I see in the scene to it's working space that I know I can work with for reproduction.
I haven't seen any visual differences of DE >25 , as that would show up like a sore thumb.
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In this kind of context, “accuracy” is a BS marketing term that can’t be defined because we’re dealing with output referred imagery. By that very context, its not accurate, its pleasing. You can’t put a matrix on pleasing, certainly not using something like deltaE!
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"Accurate" = "Boring," IMHO.
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I find it hilarious that people are complaining about lack of "color accuracy" and using non-linear tone curves, etc. Clipping blacks to boost contrast is a valid creative image adjustment, but it has nothing to do with accuracy. The same is true of using S-curves to boost contrast. If you want "accurate" colors, all of the "creative" adjustments have to be TURNED OFF.
Hm... What's about the "Camera Neutral" DNG profile with "Medium contrast" tone curve that is set as default? Colors are almost accurate there. If I set the tone curve to linearized type, I get undersaturated colors.
I do not see logic: to get accurate colors in one case I must set linearized tone curve, in another - "Medium Contrast" tone curve.
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Hm... What's about the "Camera Neutral" DNG profile with "Medium contrast" tone curve that is set as default? Colors are almost accurate there.
Accurate how? How are you defining the term? How can output referred be accurate when you can’t actually measure the scene colorimetry and compare it to the values in the output referred capture?
This may help the definition of accurate:
http://www.color.org/ICC_white_paper_20_Di...ment_basics.pdf (http://www.color.org/ICC_white_paper_20_Digital_photography_color_management_basics.pdf)
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Accurate how? How are you defining the term? How can output referred be accurate when you can’t actually measure the scene colorimetry and compare it to the values in the output referred capture?
Why I can't? When I shoot a ColorChecker SG in studio, I can. I try to get small deltas.
There are almost no problems with ICC input profiles. In studio, of course.
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Why I can't? When I shoot a ColorChecker SG in studio, I can. I try to get small deltas.
There are almost no problems with ICC input profiles. In studio, of course.
Again, I think your methodology is flawed but I’m open to hearing how you gauge this. You’ve got a target. You’ve measured the values in the scene and have Lab values? You’ve got rendered values of that image which are output referred. You’re comparing scene referred values to output referred values. Apples to oranges. Read the ICC article. It explains why scene referred looks butt ugly until its output referred. Eric explained this above too.
If anything, ICC profiles which are output referred, (the reason Adobe went another direction with DNG profiles) are farther from the goal of comparing scene and captured colorimetry.
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Again, I think your methodology is flawed but I’m open to hearing how you gauge this. You’ve got a target. You’ve measured the values in the scene and have Lab values? You’ve got rendered values of that image which are output referred. You’re comparing scene referred values to output referred values.
Yes, you are almost right (we measure spectral data of lighting also). But it does not matter at all.
Do you really think that this approach is always wrong? For all cases? (What's about digital art reproductions for example?)
Thank you, I read the ICC article earlier.
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Do you really think that this approach is always wrong? For all cases? (What's about digital art reproductions for example?)
The issue is, using a term accuracy, you need a measured matrix (which was deltaE above and which has a slew of issues all its own). Outside measuring, we can say “visually the reproduction and original match” but its nearly impossible to put a measured matrix on this when the colorimetry (the measurements of the original art work and your Epson print) don’t sync up. And someone can say “these match perfectly” and someone else can say “They are close”. Its subjective. Just as pleasing color is subjective. That being the case, using a term “accuracy” has way too much fudge factor for my taste.
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digitaldog
Andrew, thank you for for the clarification.
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Question: I have a color Checker already from X-Rite [both small and standard sizes], also a GrayScale from them, so what will this CChecker Passport give me more?
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I believe you can use the Passport software with your existing ColorChecker.
The advantage of the Passport hardware is in its design. It is better for field use because it can be snapped shut to keep debris off the patches. It can also be propped up and oriented at various angles. There are also additional patches as mentioned in Michael's review which can act as additional "white balance presets" -- creative warming/cooling, etc.
On the whole concept of accuracy and evaluation, one of the problems with doing numeric evaluations is inherent limitations of the color matching model. For example, L*a*b* comparisons via Delta E 1976, or any of the newer metrics, are based solely on colorimetry with assumed viewing conditions which often do not match the actual photographed scene conditions (e.g., photographing a ColorChecker in bright daylight versus in a dim room may lead to very similar reported L*a*b* values but very different actual appearance of the chart). You may have noticed that if you try downloading a reference ColorChecker image (Google search should turn up a few) and view it on your display, even with a well-profiled display whose gamut contains all of the patches, the tonal contrast does not look the same as the real thing.
The other problem is that optimizing for chart reproduction does not necessarily lead to better results on real images. Obviously if there is a significant problem with an existing profile (e.g., blues are coming out green) then a custom-built profile from a chart you've shot will fix that. But when one starts getting into nuances of exactly what shade of red you're looking for, it's not so clear. There are cases where optimizing for the chart (e.g., red patch) will give you a perfect hue reproduction of that patch but not so good reproduction of other real-world red colors. This can result from camera metamerism and cannot be addressed by a single color transform (profile).
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If you are trying to measure output-referred values (e.g., in Photoshop) and compare them to published reference values, they will likely be far off. In general the auto profiles created by the DNG Profile Editor and X-Rite software do not adjust the tone curve. Therefore, using these profiles within CR/LR will result in using the default tone curve within CR/LR, which has a fair amount of brightening and contrast added. Also the Blacks setting of 5 (default value in CR/LR) will step on the shadows a bit and also result in punched up colors. You can use a linearized tone curve within CR/LR by setting Brightness, Contrast, and Blacks to zero, and setting Point Curve to linear. You can then adjust Exposure so that the gray values match up reasonably well with the published chart values, assuming reasonably uniform illumination on the chart. The result will be closer to published values, but if you try to use these settings on real images, they will not look so good ...
Eric,
A very informative post. I used the profile for my D3 that I made with the DNG profile editor using Adobe Standard as the starting point and then rendered an image of the Colorchecker into aRGB with ACR default settings and then with ACR set to linear as you suggested and looked at the results with Imatest. The results are shown below graphically and the linear version closer to the nominal values:
[attachment=18055:CompositeProfiles.png]
As an interesting aside, I did note that an exposure offset of -0.5 EV is needed with the ACR defaults, whereas no offset is needed with the linear settings. Is this typical?
Bill
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As an interesting aside, I did note that an exposure offset of -0.5 EV is needed with the ACR defaults, whereas no offset is needed with the linear settings. Is this typical?
Bill
It's not surprising, given that a tone curve's main purpose is to alter luminance. Depending on the exact curve used, the net effect could be to increase or decrease overall luminance.
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Question: I have a color Checker already from X-Rite [both small and standard sizes], also a GrayScale from them, so what will this CChecker Passport give me more?
THE PASSPORT CHART HAS A FOLDING WELL DESIGNED PLASTIC CASE FOR PROTECTED HANDLING WHEN USED. THE PATCHES ARE BETTER WEATHER PROTECTED, AND THERE ARE OF COURSE THE WARMING AND COOLING PATCHES INCLUDED FOR FAST CUSTOMISATION OF YOUR SHOOTING CONDITIONS.
Ooops caps lock.
I still have some mini color checker charts, but I don't think they will see much use. Yet if you have one already then go ahead and use the X-Rite software and try out what it will do with the standard chart. The Passport really is made to be tossed in the kit bag, and becomes an accessory that is unobtrusive, but there when you need it. I still have a large SG chart but it's too big for my small gear bag, so has always been in my i1 Pro bag, usually far from any shoots outside of the studio.
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It's not surprising, given that a tone curve's main purpose is to alter luminance. Depending on the exact curve used, the net effect could be to increase or decrease overall luminance.
Is it to alter L* or gamma?
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It's not surprising, given that a tone curve's main purpose is to alter luminance. Depending on the exact curve used, the net effect could be to increase or decrease overall luminance.
That is obvious, but the extent of the exposure compensation needed with the ACR default TRC can be confusing. The BaselineExposure for the D3 is +0.5 EV. Proponents of ETTR looking at the histogram in ACR may assume that they have overexposed when the highlights are clipped and cut back on exposure for future pictures. Many have complained about Adobe's using a BaselineExposure for this reason. However, one can avoid this pitfall merely by looking at the histogram with a linear TRC. Such an exposure is not present with Nikon's own raw converter.
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Yes, I consulted for Xrite on the photographic aspects of this product, and I stressed the importance of robust packaging and in-use protection for a tool that needs to be taken to location and used there.
Edmund
Edmund. I thank you from the bottom of my heart. And camera bag.
This, (and maybe a color-fast T-Shirt with a target printed on it) could well be something that gets a Colorchecker into the hands of many, many photographers who should be using it, but don't.
I think the Lightroom plugin is brilliant. The ACR integration is a little lacking, esp. having to restart Photoshop and all, but this takes me back to the Kodak camera software, where you could build a profile right in the workflow- making it so easy and seamless that it truly made camera profiling practical. (Too bad their cameras weren't as good... )
I've posted some stuff here, in addition to everything else out there and here too...
... an intro to the thing
http://www.h2hreviews.com/blog/X-Rite-Passport.html (http://www.h2hreviews.com/blog/X-Rite-Passport.html)
a brief Lightroom explanation:
http://www.h2hreviews.com/blog/X-Rite-Pass...12;Part-2-.html (http://www.h2hreviews.com/blog/X-Rite-Passport—Part-2-.html)
and I did a little Youtube number on how you can use it.
http://www.h2hreviews.com/blog/X-Rite-Passport--Part-3-.html (http://www.h2hreviews.com/blog/X-Rite-Passport--Part-3-.html)