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Author Topic: Shooting Color Targets  (Read 9702 times)
Hening Bettermann
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« Reply #40 on: February 16, 2013, 07:53:13 PM »
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Thanks a lot to all of you! That is very useful information.
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kirkt
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« Reply #41 on: February 16, 2013, 08:02:37 PM »
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Thanks samueljohnchia for the heads up.  I'll give the linked values a try (thanks Vladimirovich) as well as the Myers values.

kirk
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samueljohnchia
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« Reply #42 on: February 16, 2013, 08:04:34 PM »
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Hening, will you be testing DCP vs ICC profiles in Irident Developer? Would be very interested to see a comparison, and how rendering the files with different edits (linear raw vs gamma corrected, default settings vs optimized to taste) interplays with the profile. Wondering if ICC profiles really would do worse than DCP. Don't have a mac so I can't test this myself.

Maybe Andrew Rodney is already doing this as I write this?
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samueljohnchia
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« Reply #43 on: February 16, 2013, 08:08:27 PM »
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Thanks samueljohnchia for the heads up.  I'll give the linked values a try (thanks Vladimirovich) as well as the Myers values.

kirk

No problem, Kirk. I think the 2 degree observer values are close to Myer's values - his should be for that observer as well. The 10 degree observer values seem a tad dark.
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Hening Bettermann
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« Reply #44 on: February 16, 2013, 08:32:57 PM »
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Hening, will you be testing DCP vs ICC profiles in Irident Developer?

I'll see what I can do.
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digitaldog
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« Reply #45 on: February 17, 2013, 11:11:42 AM »
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Maybe Andrew Rodney is already doing this as I write this?

Well I'd like to. I'd like others to try as well. I'm still trying to figure out the differences in how ID 'supports' DNG profiles. I'd like to figure out a ID or any raw converter that supports such profiles can be set to be as agnostic as possible at a stage one loads either type of profile. Do we compare custom to custom and canned to canned profiles? It also appears that one can make a DNG profile as we usually do and apply them to differing raw converters that support such profiles? That would in itself be interesting because that's not the case with an ICC camera profile. You can't even build one until you figure out how to set the raw converter to produce a rendered image to pass to the profiling software. Apparently not the case with DNG profiles (hard to argue they are less raw then what an ICC profile has to work with). All very interesting stuff.
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Andrew Rodney
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Hening Bettermann
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« Reply #46 on: February 17, 2013, 06:42:19 PM »
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Rather than conducting experiments, I have all day struggled with the basics.
 
I have taken the white balance from the second-whitest patch of the CC24, then used this as the custom WB for shooting the QP target.
Opened in ID, displayed through my normal profile, which is linear and everything zero, and WB as shot, the white patch of the ColorChecker reads 124/114/96 in the Digital Color Meter.  The WB is displayed as 5200K/+7 (DNG estimate). If I set it to 5000K/0, it gets a little better, 124/114/96. If I adjust the WB so that the RGB curves are adjusted to the same max value (that they end the same place in the right side of the histogram) then the values are 114/113/106. The WB is then displayed as 4407/+7 (DNG).

The DigitalColorMeter reads the values that the screen displays, so my calibration may be the culprit. But where do I find the values which are actually in the file? ACR and PS CS5 display similar values.

I can not shoot the target better than I did. Is the Canon swallowing Blue?

WRT Iridient Developer, the result so far is:

When I first tried, ID displayed the profiles in the profiles selection list. But I could not identify them, because: QP does not enter the name under which you save the profile in the Profile Description String. Instead, this string is always set to the name of the camera, in my case "Canon EOS 5D Mark II". At least this is true for ICC profiles - the ColorSync utility can not open DNG profiles, so I don't know.

Because ID does NOT identify profiles by their Finder name, but by the Profile Description String, it displayed these profiles as "Canon EOS 5D Mark II", "Canon EOS 5D Mark II 01", "..02" etc.

So I could not identify the profiles when I was to select one.
So I tried to put only 1 profile at a time in my profiles folder.
This implied some fiddling to and fro, re-launches of ID and re-starts of the Mac.

At some stage in the beginning, when I tried to select a profile, ID could not open it - but that was true for both DNG and ICC profiles created by QP. Now, ID does not even display them any more in the profile selection list. Understandable enough, it may have gotten confused by identical names for different profiles.

That' s the harvest of today...

BTW note that QP does not let you choose the rendering intent - it's Perceptive. So I will not go on with the QP software. If and when I get the time, I'd like to try the QP target with Argyll.

Good light (and good night) - Hening.
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samueljohnchia
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« Reply #47 on: February 17, 2013, 08:19:54 PM »
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I'd like to figure out a ID or any raw converter that supports such profiles can be set to be as agnostic as possible at a stage one loads either type of profile.

I don't know for ID, yet. For ACR/Lightroom, one must use process 2010, set all sliders to zero, tone curve linear. This provides a linear starting point. Using these settings, with a DNG PE profile with the base tone curve, it renders the CC target very closely to a synthetic target. This thread covers the Process version linearity discussion:  If one can get ID to match a PV 2010 zeroed image, I think you are at a good starting point. I will try to get my hands on a mac and try it out.

I'm more interested in comparing custom to custom. No idea how the canned profiles were produced, and even then they are not built using my own camera so I cannot use them to evaluate their performance with other real-world photos I have taken.
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samueljohnchia
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« Reply #48 on: February 17, 2013, 08:47:52 PM »
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You can't even build one until you figure out how to set the raw converter to produce a rendered image to pass to the profiling software.

I'm caught here - if I render an image in the raw convertor to produce a 16 bit ProPhoto RGB tif to feed to the profiling software, wouldn't the raw convertor be using the default camera profile to render the tif in the first place?

Then with the custom ICC profile thereafter, it would replace the default camera profile used by the raw convertor initially...  Huh

How would the custom ICC then account for the initial transform of colors with the default ICC profile?
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samueljohnchia
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« Reply #49 on: February 17, 2013, 09:50:44 PM »
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Opened in ID, displayed through my normal profile, which is linear and everything zero, and WB as shot, the white patch of the ColorChecker reads 124/114/96 in the Digital Color Meter.  The WB is displayed as 5200K/+7 (DNG estimate). If I set it to 5000K/0, it gets a little better, 124/114/96. If I adjust the WB so that the RGB curves are adjusted to the same max value (that they end the same place in the right side of the histogram) then the values are 114/113/106. The WB is then displayed as 4407/+7 (DNG).

The DigitalColorMeter reads the values that the screen displays, so my calibration may be the culprit. But where do I find the values which are actually in the file? ACR and PS CS5 display similar values.
What color space is the file you are reading the values from? The info panel in Photoshop or ACR will give you correct readouts from where your cursor is pointing. Not sure why your white patch values are so low? For ProPhoto RGB, the reference white patch value for the QP203 should be about 234/233/229, the ColorChecker should be about 242/242/238.


Okay, I managed to borrow a mac and tried to work ID.

1. I'm equally baffled by the way it handles profiles. I have a DNG profile created by the DNG PE. When I try to load it from the input profile option, it is grayed out. Try as I might I cannot get ID to load a custom DNG profile. How does one do this?

2. I also took a look at the way ID renders tone and color with all the settings zeroed out, tone curve linear. Under the "In" panel, the camera curve set to default. It appears similar to the default based tone curve embeded by the DNG PE. The resulting rendering is still too contrasty. This would not be a good starting point for evaluating profiles. Haven't found the "linear" settings yet.

-Edit-
Setting the camera curve to linear (remove all points) results in a perfectly linearized rendering from ID. The attached screenshot shows a comparison with a linearized ACR version.
« Last Edit: February 17, 2013, 10:12:38 PM by samueljohnchia » Logged
Hening Bettermann
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« Reply #50 on: February 18, 2013, 06:38:36 AM »
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> I'm caught here - if I render an image in the raw convertor to produce a 16 bit ProPhoto RGB tif to feed to the profiling software, wouldn't the raw convertor be using the default camera profile to render the tif in the first place?

I think you would disable color management in ID to produce the TIF for profile creation.
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samueljohnchia
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« Reply #51 on: February 18, 2013, 10:05:32 AM »
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I think you would disable color management in ID to produce the TIF for profile creation.

This is what no color management ends up with - all dark and muddy. I'm quite sure that creating an ICC profile for this rendering is not going to work. We need something that is gamma corrected but with no camera profile applied, i.e. convert from camera space to CIEXYZ or whatever middle color space is used, and then converted to a chosen output working space say ProPhoto RGB. Can't figure out how to do that with ID.

Also I cannot get ID to load a dng profile. How did you load yours?
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kirkt
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« Reply #52 on: February 18, 2013, 10:47:04 AM »
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Here's fun fact about QPCalibration.  If you use the QPCalibration application to create a DCP profile from a 202 or 203 card you also get a "temp.dcp" file created in the QPCalibration Application Support directory (~/Library/Application\ Support/QPcalibration/temp.dcp) - this has a linear tone curve.  If you are interested in linearized versions of the profile you are trying to generate, you can use this file.  You can decompile the DCP file in dcptool and change the profile name to make sure that it appears the way you want it in the profile list in ACR-LR.  Then recompile it back into a DCP and you are good to go.  You can also use the rename function in QPCalibration to do this as well.  That, plus PV2010 linear all sliders to zero may be useful for a linear file.

I have not examined this for ICC profiles generated with QPCalibration.

kirk
« Last Edit: February 18, 2013, 11:01:53 AM by kirkt » Logged
Hening Bettermann
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« Reply #53 on: February 18, 2013, 11:13:44 AM »
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> Also I cannot get ID to load a dng profile. How did you load yours?

As said I could not in the end. In the beginning, I just moved it into my profiles folder, and it was displayed in the profile selection list, but could not be loaded.
« Last Edit: February 21, 2013, 05:51:35 PM by Hening Bettermann » Logged

digitaldog
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« Reply #54 on: February 18, 2013, 11:29:00 AM »
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I'm caught here - if I render an image in the raw convertor to produce a 16 bit ProPhoto RGB tif to feed to the profiling software, wouldn't the raw convertor be using the default camera profile to render the tif in the first place?

The deal is, you're handing a rendered image, rendered using all the unique properties of the converter before you can profile that behavior. It's not very raw like! IF I can get more info from Brian at ID, he appears that one could build a DNG Profile that is raw converter agnostic. That is, I don't believe X-rite has any special information about the Adobe processing pipeline, I believe they build a DNG profile using the publicly open info on this spec and process. What this may mean is one could build a DNG profile and use it in ID and LR on the same raw file and assuming we could figure out a good default setting for everything else the converter does, we could have a closer apples to apples comparison of what a DNG versus an ICC profile bring to the party.

The 'issue' is that ID doesn't support the newest spec of DNG which Brian had said might cause the DNG camp to cry foul.

This is a copy and paste of one email where I was given more information about how to handle ID with profiles (Brian said it would be OK to quote him):

Quote
AR: Well it is in a way. Your product allows either to be used. So what do we need to do to test this correctly? I've still got software and a group of differing targets I could use to build an ICC camera profile.


I kind of, sort of, allow for either to be used though I think for a truly fair comparison you'd want to use the full abilities of the latest DNG v1.4 spec which includes color table based profiles that I do not support. I think DNG fans would definitely cry foul if you were to limit the DNG profiles to color matrix data only? I recommend limiting the ICC profiles to matrix only as well so still may be an interesting comparison and not really a total mismatch. In both cases I think the color matrix bit is the core part and color tables just allow for more creative tweaking...

The tricky thing with most commercial ICC profilers (been a very long time since I've used them) is that they generally are expecting to get a standard image format for profiling (like a TIFF or JPG). I remember so just could not handle 16 bits/channel or linear RAW data at all. They'd just totally fail.

So probably wisest in RAW developer to setup a camera tone curve that calibrates color chart grayscale to gamma 2.2. Definitely white balance prior to profiling especially if the camera white balance is off. Use either a gray card or with the CC chart the 2nd or 3rd patches from the left are most neutral. With the basic color checker generally the RGB reference data is given in sRGB I believe so just set up a simple tone curve in Iridient Developer that matches the reference values along the gray scale and you've basically got approx 2.2 gamma output.

ArgyllCMS will support linear data and does support 16 bits/channel. Mostly I'll linearize the camera tone curve but many cameras are quite linear already and I'll just do a quick tweaking of the white point to get the levels up to normal exposure. With recent versions of ArgyllCMS I've found it doesn't matter too much what the tone curve exactly is and I'll often now just use the colprof tool's -am. option in which case it just assumes linear gamma. In this mode I'd avoid doing an actual gamma correction of the camera tone curve for obvious reasons... Bumping up the white point to normalize exposure levels is still a good thing but in a rush I've skipped this in some cases. Doing a full accurate linearization of the grayscale would in theory give the best results in this mode as the profiles going to be output as perfectly linear even if the image data is not...

AR:I'd like to see good peer review on this subject! I'd like testing to be well defined. I'd like to see a number of savvy users (not the DP review crowed) to give the two processes a try then report their findings. Can this be done in your product, ideally even in demo mode? If so, are there specific steps one should follow to build both sets of profiles and then use them?

Demo mode will watermark images with red text which could throw off profiling tools... However, given a custom ICC profile for an image you could load that in the demo just fine for viewing.

DNG currently can only be of the original color matrix type and must be embedded into a DNG image file. No support for loading of standalone DCP format color profiles at this time in Iridient Developer at this time. So you need to profile the DNG and then embed the custom profile back into the DNG file. Again could load custom DNG profile data out of a DNG file for viewing with the demo, but I do not support export of DNG files for profiling.

for Iridient Developer to output an image for profiling:
1) Disable all color management by checking the checkbox on the Out pane of the settings window.
2) White balance the reference image if necessary
3) Adjust camera tone curve either to accurate linear gray scale or gamma 2.2 or sRGB or I've even done some work with LAB grayscale too (close to gamma 2.4). Some tools will be picky about the tone curve and will expect image data in roughly 2.2 or 1.8 gamma. Some like ArgyllCMS will work with just about anything you toss at them.
4) Export as TIFF ideally 16 bits/channel (critical for linear data) if the profiling tool supports it.

After profiling the created profile will generally be tied to the camera tone curve used above. Uncheck the disable color management option and choose the ICC profile in the Input Profile popup menu after copying to one of system ICC profile folders (/Library/ColorSyc/Profiles/ etc). You can modify the camera tone curve, but you'll lose accuracy just like you do if you modified an RGB tone curve to a carefully calibrated image from a scanner.

Most of my default camera profiles where I am not be hyper sensitive to getting accurate color I'll actually just go and modify the camera tone curve to normalize exposure and smoothly roll off highlights, etc even though the ICC profile was created under the assumption of perfectly linear data. As long as the curve is largely linear especially through the critical mid tones I think this is OK...
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Andrew Rodney
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Hening Bettermann
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« Reply #55 on: February 18, 2013, 12:03:03 PM »
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> This is what no color management ends up with - all dark and muddy. I'm quite sure that creating an ICC profile for this rendering is not going to work. We need something that is gamma corrected

The ID Help contains a section on camera profiling, where this is discussed. Copying is disabled, so I can not quote. (BTW This Help makes no claim of support for DNG profiles.)

Well I see in the meantime Andrew refers a detailed procedure given by Brian.

> DNG currently can only be of the original color matrix type and must be embedded into a DNG image file. No support for loading of standalone DCP format color profiles at this time in Iridient Developer

So this is exactly as I guessed...:-)

« Last Edit: February 18, 2013, 12:38:21 PM by Hening Bettermann » Logged

Hening Bettermann
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« Reply #56 on: February 18, 2013, 04:19:42 PM »
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I am still struggling with the basics. I have now managed to get the color balance in the ball park. However.
I have exposed after the reading of a Pentax spot meter. The raw file opened in ID, displayed through my Canon profile, which is linear, looks as exspected. The middle gray patch of the CC reads around 72 RGB. This is linear. If I apply a curve of gamma 1.8, either in ID, or on the converted TIF in my editor (PhotoLine), the middle gray patch reads around 132 RGB instead of 102-103 (ProPhoto), and the image looks all foggy. If displayed in ID with the camera default profile, the middle gray reads 106-105-107, and the image looks normal, meaning not foggy.
What's going on?
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samueljohnchia
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« Reply #57 on: February 18, 2013, 08:01:15 PM »
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That is, I don't believe X-rite has any special information about the Adobe processing pipeline, I believe they build a DNG profile using the publicly open info on this spec and process. What this may mean is one could build a DNG profile and use it in ID and LR on the same raw file and assuming we could figure out a good default setting for everything else the converter does, we could have a closer apples to apples comparison of what a DNG versus an ICC profile bring to the party.

This is going to be a most challenging task. I doubt the testing will end up fair enough for everyone. Based on X-rite's current implementation of the Passport profile building software, it very much suits the DNG 1.2v spec with no forward matrix, and it is raw converter "agnostic" because there is  no "Adobe base profile tone curve". So the raw converter applies its default camera tone curve, or else you could also turn that off. But I doubt the quality of its profiles. By quite a lot.

Another issue is what software is going to build the ICC profiles? Argyll? Different profile building softwares are going to make different decisions about how to move colors around. Are we also testing for how well a software builds a camera profile along with DNG vs ICC? We cannot do both at the same time.

As Brian said, "You can modify the camera tone curve, but you'll lose accuracy just like you do if you modified an RGB tone curve to a carefully calibrated image from a scanner." I don't see another way of getting both ACR and ID to a normalized (matching) state without tweaking some curves in ID for ICC profiles. We already know the neutral setting points for both software - all sliders zeroed and all curves linear. They match very closely, at least for my image of the CC, and differ slightly because of differing profiles.
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samueljohnchia
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« Reply #58 on: February 18, 2013, 08:22:08 PM »
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I am still struggling with the basics. I have now managed to get the color balance in the ball park. However.
I have exposed after the reading of a Pentax spot meter. The raw file opened in ID, displayed through my Canon profile, which is linear, looks as exspected. The middle gray patch of the CC reads around 72 RGB. This is linear. If I apply a curve of gamma 1.8, either in ID, or on the converted TIF in my editor (PhotoLine), the middle gray patch reads around 132 RGB instead of 102-103 (ProPhoto), and the image looks all foggy. If displayed in ID with the camera default profile, the middle gray reads 106-105-107, and the image looks normal, meaning not foggy.
What's going on?


I have no idea which middle gray patch you are referring to? The third patch or the fourth patch? Applying a gamma-correction curve will lift the shadows significantly, more so than the highlights. Perhaps this is causing the foggy look at you see?
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Hening Bettermann
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« Reply #59 on: February 19, 2013, 09:19:30 AM »
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If white is left, then the 4th patch from the left is middle gray (D 0.7). - Why does the gamma curve make the image foggy if I apply it, whereas the default rendering of ID, which of course also implies a gamma curve, does not look foggy?
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