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Thread: White card, gray card or color checker...

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    White card, gray card or color checker...

    I often include a reference card in my shots to ensure that my color temperature is somewhat accurate...

    My card has both a white and gray reference points and I use the Camera RAW eyedropper to select either of these points to get my color temperature within reasonable parameters...

    However, a book which I have recently purchased included a 24 box color checker with white, gray and black squares along with 21 other colored squares. The book doesn't really provide sufficient information regarding using this color checker...

    Why would I need to shoot a color checker? Just shooting the white/gray card seems to provide all the correction that I need...

    I also realize that the best color balance is not always the most accurate. Often, the better color balance is not quite as accurate but is more pleasing. As an example, I tend to like slightly warmer colors in portraits...

    However, if I were shooting clothing or colored fabrics which needed the results to be absolutely accurate in the colors portrayed, I could see how a color checker might be an important tool...

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    Re: White card, gray card or color checker...

    Hi Richard,

    My quick answer is that yes; with grey or white or black you can get an image neutral, but unless you have some color of a known amount in the shot, you could get the saturation wrong - i.e. the 'turn up the volume' and have it too loud

    No doubt Colin will be along with a better answer in due course

    Cheers,

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    Re: White card, gray card or color checker...

    Also, the colour checker is supposed to allow you to create a camera profile to get exact colours (like profiling your monitor). Apparently (reading from the docs with my colorchecker passport ), you'd have to create a profile for each type of lighting you use, or at least one for daylight and one for tungsten. Once done, that should be enough for normal use.

    So for really colour critical work, you could create a dedicated profile for each series of shots.

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    Re: White card, gray card or color checker...

    Hi Richard and Dave,
    I have a some questions about gray card,if you inform me I will be glad.I am using color checker passport.I always capture with passport ok.Then I open my photo at Bridge and then Camera Raw.Usually starting with white balance.And I know that at that moment passport very helpful for me to adjusting correct white balance..However after finish all corrections I am opening same photo(also color checker card inside scene) in Photoshop cs 4. I am using curves tool for color cast or color correction preparing for print house..My curves setting are Shadows 13-13-13 Highlights 242-242-242 and midtones is 128-128-128 ok?.And then with threshold I find a darkest area in the photo and then find a lightest area in the photo so on.But My many times I realize that some points has a darker tone in my photo than the color checker's black patch tone....For highlights have same confusing.What can I do, which way is right. Thank you for your help

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    Re: White card, gray card or color checker...

    Quote Originally Posted by kapkin View Post
    Hi Richard and Dave,
    I have a some questions about gray card,if you inform me I will be glad.I am using color checker passport.
    <...>
    And then with threshold I find a darkest area in the photo and then find a lightest area in the photo so on.But My many times I realize that some points has a darker tone in my photo than the color checker's black patch tone....For highlights have same confusing.What can I do, which way is right. Thank you for your help
    I'm going to guess that your darkest tone in the photo is in deep shade... so it receives less light than your colorchecker and thus will be darker than the colorchecker's black patch (which isn't perfect black, so it will still reflect some light, as will any known pigment). As for the highlights, those probably receive more light than you colorchecker, and so should appear brighter than the colorchecker white patch.

    The reference card tries to cover the whole range from black to white under flat lighting (what Colin refers to as a pure reflective scene), with no shadow/bright side differences. As soon as you get a scene with lighting variations, your tonal range can/will increase beyond the range of your colorchecker

    Extreme example: take a white ball on a black background and use hard light from the side... the shadow side will appear black, though the ball is white there as well).

    Hope this helps,

    Remco

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    Re: White card, gray card or color checker...

    Quote Originally Posted by Dave Humphries View Post
    No doubt Colin will be along with a better answer in due course
    Sorry I'm late

    Hi Richard,

    A grey card is great, but it assumes that the camera is capturing colour perfectly, and that's never the case (so the big variable becomes "how close is close enough").

    A colourcard captures known references - which can be handy, but generally were a PITA to adjust the image for ...

    ... until recently ... when the Color Passport was released (I think someone mentioned it above). Basically it's the same 24 patch card we've come to know and love - plus some other useful patches for warming portraits & cooling landscapes etc, but the "secret sauce" is profile creation software to AUTOMATICALLY create a custom camera profile every time you shoot (and it does it very very easily).

    So if it's just the card, I wouldn't get too excited, but if you use ACR and have the passport package, then you'll be smiling (you'll also be quite shocked at how the image changes when you select that profile compared to the one you're currently using!).

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    Re: White card, gray card or color checker...

    Quote Originally Posted by revi View Post
    I'm going to guess that your darkest tone in the photo is in deep shade... so it receives less light than your colorchecker and thus will be darker than the colorchecker's black patch (which isn't perfect black, so it will still reflect some light, as will any known pigment). As for the highlights, those probably receive more light than you colorchecker, and so should appear brighter than the colorchecker white patch.

    The reference card tries to cover the whole range from black to white under flat lighting (what Colin refers to as a pure reflective scene), with no shadow/bright side differences. As soon as you get a scene with lighting variations, your tonal range can/will increase beyond the range of your colorchecker

    Extreme example: take a white ball on a black background and use hard light from the side... the shadow side will appear black, though the ball is white there as well).

    Hope this helps,

    Remco
    Hi remco,
    First I want to say thanks to you to share informations with me.I want explain to you how I am using and working color checker passport when I take a photo in my studio,because maybe I am faulty about usege the color checker card..In the studio I am going to setup all flashes for the subject and adjusting all exposures and starting test shooting with color checker card passport.Same light conditions, same subject, same exposure....After shooting I am opening my photo in the adobe bridge Raw processing..After raw processing (I am checking highlight,shadows alerts,histogram,so on)..After adjustments I am openinig my photo in the photoshop cs4..For finding a darkest point or brightest point with threshold, problem is starting.When I check the darkest point (just example)in my photo,I am monitoring that the color checker card's black plastic frame is darkest point then the black patch in the card.So I am going to thinking which point is correct.Is the color checker card's Black plastic frame right point or black patch is right.
    I know that I am writing too long but I want tell you working process of mine.Maybe some where I am wrong.Maybe my card location wrong in the scene.I am looking for where is my fault.

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    Re: White card, gray card or color checker...

    Hi, I purchased a color checker (or if you are english COLOUR) when I purchased tne 1Ds Mk II a few weeks back I then setup the camera profile in ACR and IMO it gives a much better colour rendition than those offered from Adobe and remember not only can you setup for one camera if you have two or even more you can make a profile for each. If you want to see how to setup a profile take a look at( http://www.dpbestflow.org/Start-here) and look under best practices there are movies to show how to do it. As far as I can work out you only need to do it once for each camera (1 indoors with flash and 1 out) in good light (not midday)
    Hope this helps.
    Russ

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    Re: White card, gray card or color checker...

    Quote Originally Posted by russellsnr View Post
    As far as I can work out you only need to do it once for each camera (1 indoors with flash and 1 out) in good light (not midday)
    In theory yes - not quite in practice (it varies with lens selection, ISO, colour temp etc), but in practice these things are often minor.

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    Re: White card, gray card or color checker...

    I checked the documentation that I got with the colorchecker passport (thanks Colin, good tip ), and they say (p.12 in the PDF) that the white and black patches are NOT supposed to be at pure white and pure black, resp. (or 100%/RGB(255,255,255) and 0 resp.). Later (p. 28) they give the dynamic range as covering roughly 5 stops (that's for the row of 8 patches, four light, four dark), repeating again that the extremes aren't white and black.

    So you were right in noticing that your pictures had tones outside the range of the colorchecker. I assumed (wrongly, as it appears) that the card would cover the maximum range, where XRite states it doesn't.

    Apologies for the confusion caused

    Remco

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    Re: White card, gray card or color checker...

    Quote Originally Posted by Colin Southern View Post
    In theory yes - not quite in practice (it varies with lens selection, ISO, colour temp etc), but in practice these things are often minor.
    Hi, So Colin are you saying that it is better to take a photograph of the CC with each lens ? and as I use a manual WB I should also reset the WB for every lens? even if I shoot the CC for each lens at the same time to make the camera profiles?
    Many Thanks
    Russ

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    Re: White card, gray card or color checker...

    Hi Russ,

    Quote Originally Posted by russellsnr View Post
    Hi, So Colin are you saying that it is better to take a photograph of the CC with each lens ?
    In theory, yes as there are differences between lenses - but in practice, the result may well be close enough for what you want anyway. The beauty of it is though that you can now do a new profile each time you shoot if you want - or use an existing profile if you don't want to create a new one. Probably a good example of this "in action" is when I'm shooting in the studio - heaven knows I've probably trashed more prints than I care to remember due to inaccurate skintones; when I'm doing large (sometimes larger than life) prints, the skin tones really do have to be spot on - and sometimes (often in fact) any problems can't always be fixed using just white balance adjustments - and when that's the case (personally) I really struggle because when I stare at them for long enough, my brain starts "compensating" to the point where they look ok, but in reality they aren't.

    So because I need accuracy - and I have a variety of lenses - it makes sense for me to have a profile for each lens. Another variable though is the light - and it's possible that different lighting conditions can influence things as well; in the studio it's not a problem because the lighting is always the same (although even then there are variations when for example we might get some colourspill reflecting onto skin) (nothing's ever easy for a perfectionist!). So for me, in the studio, if I think of it, I'll shoot a reference card - and if I forget then no problem because I'll have the profile from other shoots anyway, which is still better than a standard profile.

    Having just said all that though, if you're outside shooting landscape for example, it's probably not going to make a big difference. For me, skin tones are where it "does it's best work". So for me camera profile - monitor profile - printer profile - gives me a totally colour-managed workflow, with predictable & consistent results.

    as I use a manual WB I should also reset the WB for every lens? even if I shoot the CC for each lens at the same time to make the camera profiles?
    I'm not sure to be honest; a RAW capture doesn't actually have a white balance - only a WB metadata tag, but I'm not sure what the profile software actually does with this (although it must do something). Don't forget though, that even with a custom profile, it's still necessary to white balance the shot (which makes sense to me, but I'm not quite sure how the camera tells the difference between what is a camera colour issue (which needs to be corrected in the profile) -v- a colour temperature issue (which doesn't). In theory (and this is only my theory) I'd say that there wouldn't be any disadvantage to doing a custom WB before shooting a reference shot for the CC (and it'll save you having to WB the shots in that series later if it's a "real / live shoot") (as opposed to just a shot for the profile). Put another way, if you don't do a manual WB first, on a "real/live shoot", even though you've shot a custom profile, you still also need to shoot a grey card and do a normal WB.

    Hope this helps.

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    Re: White card, gray card or color checker...

    I've only used a grey card and have been amazed at how much of a difference it makes.

    I have this one...
    http://www.amazon.com/Lastolite-LL-L...5423498&sr=8-2

    I love it. Not too small, not too big, folds up and fits just fine in my camera bag. You will notice a big difference in the quality of your photos.

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    Re: White card, gray card or color checker...

    Quote Originally Posted by Colin Southern View Post
    Hi Russ,



    In theory, yes as there are differences between lenses - but in practice, the result may well be close enough for what you want anyway. The beauty of it is though that you can now do a new profile each time you shoot if you want - or use an existing profile if you don't want to create a new one. Probably a good example of this "in action" is when I'm shooting in the studio - heaven knows I've probably trashed more prints than I care to remember due to inaccurate skintones; when I'm doing large (sometimes larger than life) prints, the skin tones really do have to be spot on - and sometimes (often in fact) any problems can't always be fixed using just white balance adjustments - and when that's the case (personally) I really struggle because when I stare at them for long enough, my brain starts "compensating" to the point where they look ok, but in reality they aren't.

    So because I need accuracy - and I have a variety of lenses - it makes sense for me to have a profile for each lens. Another variable though is the light - and it's possible that different lighting conditions can influence things as well; in the studio it's not a problem because the lighting is always the same (although even then there are variations when for example we might get some colourspill reflecting onto skin) (nothing's ever easy for a perfectionist!). So for me, in the studio, if I think of it, I'll shoot a reference card - and if I forget then no problem because I'll have the profile from other shoots anyway, which is still better than a standard profile.

    Having just said all that though, if you're outside shooting landscape for example, it's probably not going to make a big difference. For me, skin tones are where it "does it's best work". So for me camera profile - monitor profile - printer profile - gives me a totally colour-managed workflow, with predictable & consistent results.



    I'm not sure to be honest; a RAW capture doesn't actually have a white balance - only a WB metadata tag, but I'm not sure what the profile software actually does with this (although it must do something). Don't forget though, that even with a custom profile, it's still necessary to white balance the shot (which makes sense to me, but I'm not quite sure how the camera tells the difference between what is a camera colour issue (which needs to be corrected in the profile) -v- a colour temperature issue (which doesn't). In theory (and this is only my theory) I'd say that there wouldn't be any disadvantage to doing a custom WB before shooting a reference shot for the CC (and it'll save you having to WB the shots in that series later if it's a "real / live shoot") (as opposed to just a shot for the profile). Put another way, if you don't do a manual WB first, on a "real/live shoot", even though you've shot a custom profile, you still also need to shoot a grey card and do a normal WB.

    Hope this helps.
    Ok Colin thanks for that. As I am mostly outdoors I tend to take a manual WB as I move around or the light moves ( I use an expo disc) and as you say there is not a great differance in the camera profile for each lens but every little helps.
    Russ

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    Re: White card, gray card or color checker...

    Yes, I have a grey card, white card, black card and have tried profiling but at the end of the day I blow it all out of the water and adjust colour balance within my workflow to get the 'feel' I want in the image, so I tend not to bother any more. I tend not to take colour critical shots as you will have gathered.

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    Re: White card, gray card or color checker...

    Quote Originally Posted by Colin Southern View Post
    <...>
    I'm not sure to be honest; a RAW capture doesn't actually have a white balance - only a WB metadata tag, but I'm not sure what the profile software actually does with this (although it must do something). Don't forget though, that even with a custom profile, it's still necessary to white balance the shot (which makes sense to me, but I'm not quite sure how the camera tells the difference between what is a camera colour issue (which needs to be corrected in the profile) -v- a colour temperature issue (which doesn't).
    The camera doesn't care about either WB or colour correction, it'll just store the raw data with a WB tag, as you said. All the colour correction stuff is post-production...

    The profiling software has to correct for the colour temperature (WB) of the incoming light in order to know how each patch should look: more red in the light would mean more red reflected, and the software has to correct for that.

    In theory (and this is only my theory) I'd say that there wouldn't be any disadvantage to doing a custom WB before shooting a reference shot for the CC (and it'll save you having to WB the shots in that series later if it's a "real / live shoot") (as opposed to just a shot for the profile). Put another way, if you don't do a manual WB first, on a "real/live shoot", even though you've shot a custom profile, you still also need to shoot a grey card and do a normal WB.

    Hope this helps.
    There's two things we want to correct here, one is a camera issue, the other an environment issue. And those two issues are independent of one another.
    The environment issue is the WB to correct for varying light colour temperatures.
    The camera issue is the profiling required to correct for non-ideal colour responses from the sensor.

    As I said, these two are independent, you could profile a sensor by illuminating it with light of known spectral composition and checking the response.

    Where things get complicated, is that we use patches of known colours, that are illuminated by an external light source. If the colour of the incoming light changes, the colour of the reflected light will change as well, so the same patch would give a different response under different light sources. In order to correct for that, we have to set the proper WB before calculating the profile. That is also why it's best to use each profile only for the colour temperature for which it was created (although XRite suggests that 2 profiles are enough to cover almost all situations, with their dual illuminant profiles).

    Remco

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    Re: White card, gray card or color checker...

    Quote Originally Posted by revi View Post
    The profiling software has to correct for the colour temperature (WB) of the incoming light in order to know how each patch should look: more red in the light would mean more red reflected, and the software has to correct for that.
    Yes - the question I don't know the answer to is is the software using the WB tag at all

    Where things get complicated, is that we use patches of known colours, that are illuminated by an external light source. If the colour of the incoming light changes, the colour of the reflected light will change as well, so the same patch would give a different response under different light sources. In order to correct for that, we have to set the proper WB before calculating the profile.
    I don't think so - I suspect it's calculating the WB itself using the grey patches

    That is also why it's best to use each profile only for the colour temperature for which it was created (although XRite suggests that 2 profiles are enough to cover almost all situations, with their dual illuminant profiles).
    Depends on what you're doing. In the studio the single illuminant is fine - no interpolation or extrapolation required. Adobe use dual illuminate profiles in ACR.
    Last edited by Colin Southern; 15th May 2011 at 08:59 AM.

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    Re: White card, gray card or color checker...

    Quote Originally Posted by Colin Southern View Post
    <...>
    I don't think so - I suspect it's calculating the WB itself using the grey patches
    <...>
    Hmm, that might be possible.
    Sounds a bit iffy to me though, as the sensor isn't profiled yes, so any colour errors would influence the gray patches as well. Otoh, an error in the WB setting is probably worse...

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    Re: White card, gray card or color checker...

    Quote Originally Posted by revi View Post
    Hmm, that might be possible.
    Sounds a bit iffy to me though, as the sensor isn't profiled yes, so any colour errors would influence the gray patches as well. Otoh, an error in the WB setting is probably worse...
    Hence my original ponderance of does it do anything with the WB metadata tag - or put another way - if the current WB isn't correct, does it induce a profile error.

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