Color checker passport dual illumination on Canon 350D / Rebel XT

KMBphotographicKMBphotographic Big grinsRegistered Users Posts: 17 Big grins
edited January 4, 2013 in Technique
I have recently started using an X-rite Color Checker Passport with my Canon 550D (Rebel T2i) to make a dual illuminant profile and it works remarkably well. However, I have not had the same success with making a dual illuminant profile with my Canon 350D (Rebel XT, but has Kiss Digital N branding on the outside)...

...the error message I get when I try to follow the same method on my Canon 350D as I (successfully) followed for my 550D reads: "Could not generate profile because one or more images have unsupported illuminants". I have tried using different pairs of illuminants (all of which worked for my 550D) such as flash + tungsten, flash + fluorescent, cloudy + tungsten etc, and setting the white balance to the type of light (flash, or tungsten etc so that the EXIF keyword corresponds to the correct type of illumination).

Does anyone know if the header/EXIF information is written differently in the earlier Canons compared with the later ones? I am wondering if the Color Checker Passport software isn't correctly understanding the header/EXIF information from the older camera, but what may argue against this is that the software does a very good job with making a single illumination profile for my 350D (astoundingly good actually, and this 350D has been infra-red adapted so there is no longer an infra-red blocking filter on this camera - everything looks jolly red unless corrective measures are taken).

I should be very grateful if anyone can shed any insights into how I might be able to successfully generate a dual illuminant profile for my 350D from the X-rite Passport software.

Many thanks, Katherine

Comments

  • arodneyarodney Major grins Registered Users Posts: 2,005 Major grins
    edited December 21, 2012
    Did you try the DNG's in Adobe's DNG profile creator to see if this is an X-Rite bug? The software is free on Adobe Labs and while I prefer the DNG profiles from the X-Rite software, the differences are not large. If you can't create a profile using the Adobe software, time to report a bug to them and X-Rite. But it could be an X-Rite Passport software issue.
    Andrew Rodney
    Author "Color Management for Photographers"
    http://www.digitaldog.net/
  • KMBphotographicKMBphotographic Big grins Registered Users Posts: 17 Big grins
    edited December 21, 2012
    arodney wrote: »
    Did you try the DNG's in Adobe's DNG profile creator to see if this is an X-Rite bug? The software is free on Adobe Labs and while I prefer the DNG profiles from the X-Rite software, the differences are not large. If you can't create a profile using the Adobe software, time to report a bug to them and X-Rite. But it could be an X-Rite Passport software issue.

    No - I hadn't tried this (or indeed come across Adobe DNG Profile Editor previously...). Many thanks for this suggestion - I'll investigate and report back... Actually, just a question - their documentation says to "Photograph [their 24 patch] ColorChecker Chart". Obviously for this exercise I can't photograph my monitor, but presumably I can simply use the X-rite ColorChecker 24-patch Passport (the arrangement of colours seems to correspond between both the Adobe and the X-rite charts)?

    Many thanks again,

    Katherine
  • arodneyarodney Major grins Registered Users Posts: 2,005 Major grins
    edited December 21, 2012
    The Xrite Passport has the 24 patch Macbeth, correct.
    Andrew Rodney
    Author "Color Management for Photographers"
    http://www.digitaldog.net/
  • KMBphotographicKMBphotographic Big grins Registered Users Posts: 17 Big grins
    edited December 22, 2012
    I've just tried feeding DNG files from the Canon 350D to the Adobe DNG Profile Editor, but get the error message "Non-neutral gray patches. The gray patch in row 4, column 5 has a significant color cast. Please reshoot the chart carefully to avoid color casts and try again." Curiously, I get the exact same error with DNG files from the 350D if I first do a white balance in Lightroom-4.2 (with the eyedropper on the exact gray patch the error messages refers to, so that to my eyes the image of the ColorChecker card looks white-balanced for the neutral patches (if a little flat for the coloured patches)).

    DNG files from my 550D work perfectly when fed into Adobe DNG PE.

    I'd be grateful for any suggestions of what I could try next.

    Many thanks, Katherine
  • arodneyarodney Major grins Registered Users Posts: 2,005 Major grins
    edited December 22, 2012
    There is a DNG forum for Adobe which you could report. Otherwise can you upload one DNG for us to examine on another system to rule that out. How did you convert the Passport images to DNG? Did you use the latest DNG converter or Lightroom?
    Andrew Rodney
    Author "Color Management for Photographers"
    http://www.digitaldog.net/
  • KMBphotographicKMBphotographic Big grins Registered Users Posts: 17 Big grins
    edited December 22, 2012
    arodney wrote: »
    There is a DNG forum for Adobe which you could report. Otherwise can you upload one DNG for us to examine on another system to rule that out.

    That would be very kind.

    Um... I can't attach a DNG file to this dgrin forum (it's not gif, jpeg, jpg, mml, kHz, pdf, png or txt) and when I try to upload to Smugmug it says "wrong file type" (for the 550D DNGs as well).

    Should I be able to upload a DNG file to dgrin?
    How did you convert the Passport images to DNG? Did you use the latest DNG converter or Lightroom?

    Lightroom-4.2 (for both my 350D and 550D exports from RAW to DNG).

    Many thanks,

    Katherine
  • arodneyarodney Major grins Registered Users Posts: 2,005 Major grins
    edited December 22, 2012
    You Send It would be a better option to upload a larger document to more than one person.
    Lightroom-4.2 (for both my 350D and 550D exports from RAW to DNG).

    What settings used for conversion?
    Andrew Rodney
    Author "Color Management for Photographers"
    http://www.digitaldog.net/
  • KMBphotographicKMBphotographic Big grins Registered Users Posts: 17 Big grins
    edited December 22, 2012
    arodney wrote: »
    You Send It would be a better option to upload a larger document to more than one person.

    I've just PM'd you with a link.
    What settings used for conversion?

    In File Settings, I used the default parameter values, namely:
    Image Format: DNG
    Compatibility: Camera Raw 5.4 and Later
    Embed Fast Load Data selected
    Embed Original Raw File unselected

    Many thanks,
    Katherine
  • arodneyarodney Major grins Registered Users Posts: 2,005 Major grins
    edited December 22, 2012
    I was able to build a DNG profile in Lightroom 4.2 using the Passport plug-in as well as using the Adobe DNG profile editor. The image is grossly ugly (off white balance) but that doesn't affect the raw and in LR I did a quick WB in 2nd white patch before exporting. So it's something on your system, the DNG's and software (on 10.8) work fine.
    Andrew Rodney
    Author "Color Management for Photographers"
    http://www.digitaldog.net/
  • KMBphotographicKMBphotographic Big grins Registered Users Posts: 17 Big grins
    edited December 22, 2012
    arodney wrote: »
    I was able to build a DNG profile in Lightroom 4.2 using the Passport plug-in as well as using the Adobe DNG profile editor. The image is grossly ugly (off white balance) but that doesn't affect the raw and in LR I did a quick WB in 2nd white patch before exporting. So it's something on your system, the DNG's and software (on 10.8) work fine.

    The gross off-whiteness is because it's an infra-red adapted camera (doing an initial white balance in Lightroom didn't alter any of the behaviour I saw when attempting to build profiles).

    Did you succeed in building a dual illuminant profile? I could get the single illumination to work, but it's the dual I had all the problems with and was wanting to overcome.

    Many thanks,

    Katherine
  • arodneyarodney Major grins Registered Users Posts: 2,005 Major grins
    edited December 22, 2012
    The gross off-whiteness is because it's an infra-red adapted camera (doing an initial white balance in Lightroom didn't alter any of the behaviour I saw when attempting to build profiles).

    That alone could be the issue with the errors you got about balance.

    I only ended up with one DNG so I didn't make a dual illuminant profile. You can't do that in Lightroom anyway, you have to use the Passport software.
    Andrew Rodney
    Author "Color Management for Photographers"
    http://www.digitaldog.net/
  • MarkRMarkR Accused Shill. Registered Users Posts: 2,099 Major grins
    edited December 22, 2012
    I've just tried feeding DNG files from the Canon 350D to the Adobe DNG Profile Editor, but get the error message "Non-neutral gray patches. The gray patch in row 4, column 5 has a significant color cast. Please reshoot the chart carefully to avoid color casts and try again." Curiously, I get the exact same error with DNG files from the 350D if I first do a white balance in Lightroom-4.2 (with the eyedropper on the exact gray patch the error messages refers to, so that to my eyes the image of the ColorChecker card looks white-balanced for the neutral patches (if a little flat for the coloured patches)).

    DNG files from my 550D work perfectly when fed into Adobe DNG PE.

    I'd be grateful for any suggestions of what I could try next.

    Many thanks, Katherine

    This often happens in the Adobe DNG tool because either a) you forgot to drag the little color dots to the corners of the Colorchecker before trying to build a profile, (I know this because a ... friend ... had this problem once) or b) there is some other thing going on that is preventing the Adobe tool from identifying the color checker patches correctly.

    My own limited experience is that the Adobe profile creator will give a much more neutral look, one that should theoretically be similar to the Adobe Standard profile. X-rite profiles seem much contrastier and saturated to my eye.

    Jeff Schewe had a wonderful post on some message board (that I can't find) about how Adobe creates it's profiles. The take-away for me was that the Adobe profile is usually preferable, unless the sample camera Adobe used to create it is significantly different in color rendering for your own camera. I actually had this happen to me when I owned a Pentax K20d. The canned standard profile was so far off that every image needed some sort of color correction, and skin tones were a nightmare-- until I created a custom profile. Now I've moved to Nikon and I find that the Adobe Standard to be better than anything I've been able to create in terms of being able to be applied across a range of images.
  • ziggy53ziggy53 Still learnin'still lovin Super Moderators Posts: 22,326 moderator
    edited December 26, 2012
    The gross off-whiteness is because it's an infra-red adapted camera ...
    arodney wrote: »
    That alone could be the issue with the errors you got about balance.

    ...

    Katherine, almost certainly, and as Andrew says, the IR converted camera is the issue. While you don't mention who did the conversion, the type of conversion ("IR plus visible" vs "IR only", for instance) or the level of conversion (if "IR only" it may be either near IR or deep IR), it's likely that you will get almost no blue-channel output if it's an "IR only" conversion. Even an "IR plus visible" will have a distorted sensitivity compared to a standard visible light camera.

    I'm not sure that creating a dual-illuminant profile for that body has any practical merit for IR digital photography.

    I have a Canon XT/350D, with a 720nm Life Pixel, "IR only" conversion. (Their "Standard" IR conversion.)

    If you could detail what conversion you have, and who did it, and if you can further explain your intended use for the camera, we might be able to describe a methodology and technique to give you desirable results.
    ziggy53
    Moderator of the Cameras and Accessories forums
  • KMBphotographicKMBphotographic Big grins Registered Users Posts: 17 Big grins
    edited December 27, 2012
    ziggy53 wrote: »
    Katherine, almost certainly, and as Andrew says, the IR converted camera is the issue. While you don't mention who did the conversion, the type of conversion ("IR plus visible" vs "IR only", for instance) or the level of conversion (if "IR only" it may be either near IR or deep IR), it's likely that you will get almost no blue-channel output if it's an "IR only" conversion. Even an "IR plus visible" will have a distorted sensitivity compared to a standard visible light camera.

    I bought the camera from a friend in its adapted state and I'm not sure which company did the conversion, but I believe the conversion comprised just the removal of the IR blocking filter inside the camera so that it is now IR+visible. When I do IR photography I put an optical blocking filter on the front of the lens (e.g. 720nm or 860nm).
    I'm not sure that creating a dual-illuminant profile for that body has any practical merit for IR digital photography.

    My hope was that if I could colour calibrate the camera in its IR+visible adapted state that it would then become a useable visible camera as well: the colour profiling wasn't intended for IR photography per se. The single-illuminant profile strategy certainly works rather well (I'll upload four images presently that show this) demonstrating that the images from this adapted 350D are colour-calibratable, so my question was why should there be problems with the dual-illumiant strategy. I was hoping to generate a dual-illuminant profile for this camera rather than having to generate a fresh single-illuminant profile for every different lighting situation I would be shooting in.
  • KMBphotographicKMBphotographic Big grins Registered Users Posts: 17 Big grins
    edited December 27, 2012
    Image straight out of camera (taken under flash, no filter of any kind on the lens):
  • KMBphotographicKMBphotographic Big grins Registered Users Posts: 17 Big grins
    edited December 27, 2012
    Same image filter as above, but with simple white balance done in Lightroom (4.3). The red cast is done, but the colours look a bit flat and murky to me.
  • KMBphotographicKMBphotographic Big grins Registered Users Posts: 17 Big grins
    edited December 27, 2012
    Starting back with the original SOOC camera image, this one had the X-rite Color Checker Passport profile generated from it applied to itself (no white balancing). The colours are a lot less flat, but the red cast remains.
  • KMBphotographicKMBphotographic Big grins Registered Users Posts: 17 Big grins
    edited December 27, 2012
    This image is the same as the CCP one above, but with a white balance applied in Lightroom as the final step. The colours aren't at all flat and pop well, and the red cast is gone, demonstrating that images from this IR+visible camera can be colour calibrated with a single-illuminant profile. (I'd love to be able to calibrate via a dual-illuminant profile from it however.)
  • ziggy53ziggy53 Still learnin'still lovin Super Moderators Posts: 22,326 moderator
    edited December 27, 2012
    To use this body as a normal visible light camera you should add an IR cutout (IR blocking) filter to the lens. Then it should be possible to do the dual-illuminant profile.

    A camera profile only really makes sense when the camera used is working to the range of sensitivity and limits of the profiling software. An IR+visible camera will produce copious additional red channel in most lighting situations, skewing the results of profiling software designed for visible-only sensors. Profiling for the visible-only component of the sensor (with the IR cutout filter on the lens) should allow the software to do its job within its design parameters.

    Using the visible-only profile on a visible+IR capture should result in a fairly normal blue channel, with slightly to somewhat saturated green channel, but highly saturated red channel (because there is no IR channel, so the IR information is translated as red channel.)

    An additional custom curve for both green channel and (mostly) red channel should give you some control over the IR component of the image. The custom curve set would probably vary by the IR to visible ratio, which should vary by the lighting situation. You would further adjust the red curve by the intent for the image.

    One problem I should mention is that most IR+visible bodies are not AF compensated for the IR component. Using the body for IR only or IR plus visible will probably not properly AF the IR subjects. This may add to the IR "glow" of IR+visible captures, but IR only captures will likely need manual focus.
    ziggy53
    Moderator of the Cameras and Accessories forums
  • arodneyarodney Major grins Registered Users Posts: 2,005 Major grins
    edited December 27, 2012
    My hope was that if I could colour calibrate the camera in its IR+visible adapted state that it would then become a useable visible camera as well

    Doubtful. I think the rabbit hole you've been lead through with DNG Profiles is based on this assumption.
    Andrew Rodney
    Author "Color Management for Photographers"
    http://www.digitaldog.net/
  • KMBphotographicKMBphotographic Big grins Registered Users Posts: 17 Big grins
    edited December 31, 2012
    arodney wrote: »
    Doubtful. I think the rabbit hole you've been lead through with DNG Profiles is based on this assumption.

    The fourth image I uploaded (marked "CCP then WB") shows that the profile works well when generated from a single illuminant - and hence becomes a useable visible camera. What puzzles me is why a single illuminant gives a good calibration for this camera but that dual illuminants should fail.

    Happy New Year,

    Katherine
  • KMBphotographicKMBphotographic Big grins Registered Users Posts: 17 Big grins
    edited December 31, 2012
    Many thanks for your replies.
    ziggy53 wrote: »
    To use this body as a normal visible light camera you should add an IR cutout (IR blocking) filter to the lens. Then it should be possible to do the dual-illuminant profile.

    Interesting thought... but wouldn't this calibration then only be appropriate to use for images shot with an IR-blocking filter in place?
    ziggy53 wrote: »
    Using the visible-only profile on a visible+IR capture should result in a fairly normal blue channel, with slightly to somewhat saturated green channel, but highly saturated red channel (because there is no IR channel, so the IR information is translated as red channel.)

    I agree that the red channel would be higher than the green and blue ones, but would it inevitably be saturated? I checked the histogram that the red channel wasn't clipping.
    ziggy53 wrote: »
    One problem I should mention is that most IR+visible bodies are not AF compensated for the IR component. Using the body for IR only or IR plus visible will probably not properly AF the IR subjects. This may add to the IR "glow" of IR+visible captures, but IR only captures will likely need manual focus.

    Yes indeed - I have a lower fraction of IR keepers than that from my visible-only camera!

    Happy New Year,

    Katherine
  • ziggy53ziggy53 Still learnin'still lovin Super Moderators Posts: 22,326 moderator
    edited January 3, 2013
    I sent X-Rite a request for information which might shed more details on the issues of using X-Rite Color Checker system with a visible+IR camera. The initial response from them was not even relevant, so I followed up yesterday with this message:

    "Hi [Tech Support person's name],

    My question is whether a visible-light-plus-infrared dSLR is compatible with the X-Rite Color Checker system? In other words, can you do dual-illuminant profiles which give meaningful results regarding a camera with a sensor capable of both visible and infrared sensitivity?

    Unfortunately, I don't see any mention of infrared in any of your Color Checker documentation, including the PDF you included in your response. As such, it's probably not fair to draw conclusions.

    Please consider forwarding this request for information to your research and development and product engineering departments, since this is a rather unusual area of expertise.

    Thanks for your kind attention,

    [ziggy]"


    ... to which they responded:

    "Case Subject: Dual illuminant profiles
    Product:

    Dear [ziggy],

    In an effort to resolve your support Case, the following comment has been added. Please review this comment, and respond as indicated.

    Comment: We have not done any testing of the dual-illuminant mode with infrared light conditions. This would not be a common situation for the target audience for ColorChecker Passport users.

    The ColorChecker Passport is designed for people who shoot RAW in either Lightroom or Photoshop, and will create a DNG profile that these Adobe programs can use.

    You can certainly try to build such a profile, but we have no "yardstick" for you to use in terms of determining "how accurate" such a profile would be.

    Thank you,

    [Representative's name]
    Technical Support Rep - Level 2

    X-Rite Incorporated
    4300 44th St SE
    Kentwood MI 49512 US"


    I interpret this as meaning that the Color Checker system is not designed for, and does not take into account, a camera with InfraRed sensitivity, including a camera with both Visible and IR sensitivity.


    My own thought is that, while you may encounter "some" situations where the Color Checker system seems to work fairly well (and I qualify those situations as lighting with little to no IR component and subjects with little to no IR reflectance), you will most certainly encounter situations of lighting with high levels of IR "and" subjects with high IR reflectance, and your Color Checker system profiles will provide unusual to even unpleasant results in some of the second scenario (IR rich lighting with IR reflective subjects).

    However, some of the second situation may be pleasant and even beautiful, since you may experience a non-normal tonality. For instance, human skin may experience a very nice "glow" in a high-IR-plus-visible lighting situation.

    I recommend experimentation, but if you truly want to use the Color Checker system to color balance visible light images with that body, then you must use an IR-cutout/cut-off filter. I suggest using an X-Nite "CC1" color correcting filter, although I have no direct experience with it. (Reviews are generally good.)
    ziggy53
    Moderator of the Cameras and Accessories forums
  • KMBphotographicKMBphotographic Big grins Registered Users Posts: 17 Big grins
    edited January 4, 2013
    ziggy53 wrote: »
    I sent X-Rite a request for information which might shed more details on the issues of using X-Rite Color Checker system with a visible+IR camera. The initial response from them was not even relevant, so I followed up yesterday with this message: [...]

    It's very kind of you to have written to X-rite about this - thanks so much!

    I certainly intend to do some experimentation (when I have got hold of an IR-blocking filter for one of my lenses...) and try and figure out how to decouple the illumination-independent calibration of the relative responses of the blue, green and (super-)red pixels in my detector from the different illumination characteristics.

    I'll report back in due course... many thanks again.
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