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Thread: White Balance w/ LCC and C1

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    White Balance w/ LCC and C1

    Perhaps this has been covered, but what do folks do for white balance? My workflow is pretty standard for back-shifted pano's with a tech cam (one LCC per exposure). However when I open RAW files (IQ 160) in C1, in the color tab, "Phase One P65+ Flash V2" is the default ICC profile and the default curve is "film standard".

    In my workflow I first change, in the ICC profile to "Phase One P65+ Outdoor Daylight" and the curve to "Linear Response". I then use the eye dropper in the White Balance tab on the middle of each LCC for grey. Next I apply these new settings for these Base Characteristics and White Balance to associated image frame (LCC was previously applied to the frame).

    Is this how others set white balance or is there a better way (other than using a Greteg card)?
    Thanks!
    Bob

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    Re: White Balance w/ LCC and C1

    Bob,

    I follow a similar approach for my images, although the grey point for white balance from the LCC is really only a starting point. I typically will apply that and then adjust it to taste on one of the images and then use that for the pano set.

    Using the LCC alone is tricky though for all cases as it picks up the colour of the subject in addition to the ambient scene. Sometimes the LCC colour cast can be pretty extreme I've found.

    Another approach I often take is to shoot an XRite Colour Checker Passport and set a custom white balance for the IQ back. Other times I'm shooting just with the back on daylight though.
    Remember: adventure before dementia!

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    Re: White Balance w/ LCC and C1

    I use WhiBal, pretty satisfied with it.
    WhiBal White Balance Gray Card Video Tutorial by Michael Tapes
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    Re: White Balance w/ LCC and C1

    In a still life shooting, I shoot LCC and gray card both. And apply the LCC correction to the gray card first. And then using the gray card shot( LCC correction applied), I set the neutral white point. The gray card shot without LCC applied, can be tricky. I alway try to shoot the gray card in the center of the frame just in case I forget shooting the LCC. The gray card positioned outside of center area of frame, is not correct in many cases.... of still-life setting.
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    Re: White Balance w/ LCC and C1

    I have started shooting the color checker passport and then picking a grey from the shot with the eyedropper tool of the back and setting WB that way.

    As Graham pointed out the LCC often seems to pick up tone/ temp from the surrounding scene. Especially late afternoon sunsets where often I get an extreme yellow cast.

    Having the color checker shot is a great tool to work the files with later on. It doesn't have to be in sharp focus either.

    Paul Caldwell
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    Re: White Balance w/ LCC and C1

    Thanks everyone!

    There is still a remaining, unanswered question...
    When processing in C1, what are the best settings to use in the color tab for ICC profile (i would assume P65+ Outdoor for my IQ160) and for the curve (I am currently using Linear Response).

    Does it matter?
    Thanks in advance,
    Bob

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    Re: White Balance w/ LCC and C1

    Generally speaking, Film standard is best. If you are shooting outside, "Outdoor" setting should be good. And then, if you want, you can try .. if another setting( like flash V2) is better for a specific image or not. If you want a simple answer..."Outdoor" and "film standard" should be good for most outdoor images...
    And if I remember correctly, "film standard" rendering is very close with my experience of 4 by 5, B&W and color chromes in overall feelings regarding contrast and colors.

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    Re: White Balance w/ LCC and C1

    Regarding intents and ICC, I use Outdoor too rather the default Flash setting.

    For images that I expect to work completely as a final image out of C1 I find that Film Standard is a good choice as it has extra contrast. For images that I expect to work as a fine art type of image using Photoshop I find that the linear rendering is closest to what I captured and metered off my MFDB and the lower contrast image is a better starting point for PS work.
    Remember: adventure before dementia!

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    Re: White Balance w/ LCC and C1

    Thanks very much Graham and Studio.

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    Re: White Balance w/ LCC and C1

    Yes, LCCs do pick up ambient colors on location, not just as a whole WB, but for example a bright color in lower half of frame (green field in sunshine?) will put a cast on the lower half of LCC. That will be wrongly corrected out by LCC creation, removing some of the color for that part of the frame when applied. These issues make a good argument for having a library of LCCs for general settings in situations where an LCC might 'over correct'. Obviously such LCC images are made in neutral flat field studio conditions.
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    Re: White Balance w/ LCC and C1

    I am doing a art repro on a large painting and color needs to be even and accurate
    So best scenario for multi frame stitch (i am doing 6 frames using credo80, flex adaptor, P2, SK 120 makro-symmar) may be to shoot LCC over lens after each frame, and a gray card/colorchecker in center frame(s) only. Write down exact settings on P2 for each. Then when back at studio, use exact same lights but shoot LCC in controlled environment for perfect wb?
    I only want to apply one wb and settings to all frames in stitch, but each shot will need its own LCC to correct fall off and color cast, correct?

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    Re: White Balance w/ LCC and C1

    I still use the film curve, as with the 160 and 260 files, it's not as harsh as it was on my P45+ files. With those it way to often pushed the highlights too far.

    My shooting environment sounds similar to yours, outdoor, shifting (mainly horizontally).

    As Graham pointed out, the LCC can take on very strange colors, especially if I try to take on with a CLPL and ND combo.

    For the LCC, now I tend to take off the CL-PL and even the ND sometimes which seems to help. When I open the LCC in C1, I also move to the daylight icc, (never have been sure why Phase One/Capture One can't read the setting off the back?). If the LCC after Capture One has converted it still seems to have non neutral grey look. I will go ahead and WB the LCC.

    On the corresponding image file, I will try to start with the corrected WB I received from the WB adjustment to the LCC, but many times I don't like the look of this.

    I try to remember to shoot a color checker card for each setup, and I have found that it seems to give the best overall reference place for starting on the image file. I have a separate folder where I keep all of the raw that were shot of a color checker so I can find them quickly as many times a color checker shot from an earlier shoot in similar lighting conditions will work as long as it was taken with the same back.

    Paul C

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    Re: White Balance w/ LCC and C1

    Thanks, paul!
    I show an example of simple shifts using the flex adaptor to the extremes of the image circle. The image here is actually 3 frames stitched showing the shift in color and density (120 Makro-Symmar)
    At first I panicked, but Doug at DT told me that this is normal and that is what LCC is for. So I am watching vids and reading up as fast as I can on doing this today!

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    Re: White Balance w/ LCC and C1

    Egor,

    A disturbing result, but a great illustration of the problem.

    Steve

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    Re: White Balance w/ LCC and C1

    Quote Originally Posted by stephengilbert View Post
    Egor,

    A disturbing result, but a great illustration of the problem.

    Steve
    Yeah, I will be doing a few single non-stitch frames and an overall with the DF just to CMA

    Jack says that even after LCC it will require work to get the whole thing to look even...scary

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    Re: White Balance w/ LCC and C1

    Egor,

    That is interesting indeed. Is the hard line shift in the image after you apply the LCC?

    Paul C

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    Re: White Balance w/ LCC and C1

    Paul, the hard line is simply the edge of each frame overlapping. The actual problem is not linear but gradated. I just lined up 3 frames there for example.
    The area on right is with the back shifted to the left most "red-dot". The area in the middle is of course the center, and the area on the left (yellowest) is with the back shifted all the way to the right.
    I will know more about how well LCC corrects this when I get into studio this morning. I have baby duty for another hour then back to the setup. Then to the job site for the shoot tonight.

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    Re: White Balance w/ LCC and C1

    The 80 with it's small pixel size is quite sensitive to pixel vignetting and crosstalk, much more so than the 60. I suggest that even after LCC correction that you try to match a color checker shot in the center of the image circle and one at the edge with the sensor shifted (as much as you need for your reproduction work). Match them by color picker on white (ie only white balance). If you see a saturation difference or some strange color shift of one or more colors you have crosstalk. The 120mm is a long lens though so I would be surprised if there are problems.

    Also note that LCC needs a reference color (figure out a reference white), and as far as I know C1 picks it from the LCC shot itself, ie if you have three LCC shots you may get a slight different reference color in each so you need to manually match them afterwards anyway. With my own Lumariver HDR you can pick one LCC shot as "anchor" (which would be the center LCC where there is the least color cast) to make sure all shots in a stitch get the exact same white balance, but I'm not sure if C1 has a corresponding feature. Maybe there are fixed presets?
    Last edited by torger; 8th March 2014 at 13:20.

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    Re: White Balance w/ LCC and C1

    Concerning linear vs film curve it's good to know that the ICC profiles for Capture One has been designed with a particular curve applied, ie the default film curve. As the ICC profiles are non-linear and the curves are applied in RGB space a slightly different color result will occur when you switch curve. It may still be pleasing, but to get the color as the profile designer intended you should use the same curve as the ICC profile was designed for.

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    Re: White Balance w/ LCC and C1

    1st test out of the box! Good...very good! I have to run down to the job site now to check on scaffold construction then back here to the lab for more testing.
    I am showing same test as before with simple LCC correction as outlined in C1-v7.2 video, wb performed after LCC applied, then output full res, stitched in photoslop, then a very minor levels adj applied to even out the edges.

    Very happy so far

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    Re: White Balance w/ LCC and C1

    What I love about this is that it could be described as one of those MasterCard ads....:

    Camera Gear = $70K
    Labor and Scaffolding = $10K
    Famous work of art = $30M

    20cents worth of white plastic and some masking tape to make it all work = PRICELESS

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    Re: White Balance w/ LCC and C1

    Btw in case folks haven't noticed it, they added an option in C1 7.2 to set the default ICC for the camera by model. So now landscape folks can set their ICC to Outdoor Daylight/Film curve vs Flash v2.
    Last edited by GrahamWelland; 8th March 2014 at 16:11.
    Remember: adventure before dementia!

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    Re: White Balance w/ LCC and C1

    I missed that! Great news tks.

    Paul C

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    Re: White Balance w/ LCC and C1

    Quote Originally Posted by torger View Post
    The 80 with it's small pixel size is quite sensitive to pixel vignetting and crosstalk, much more so than the 60. I suggest that even after LCC correction that you try to match a color checker shot in the center of the image circle and one at the edge with the sensor shifted (as much as you need for your reproduction work). Match them by color picker on white (ie only white balance). If you see a saturation difference or some strange color shift of one or more colors you have crosstalk. The 120mm is a long lens though so I would be surprised if there are problems.

    Also note that LCC needs a reference color (figure out a reference white), and as far as I know C1 picks it from the LCC shot itself, ie if you have three LCC shots you may get a slight different reference color in each so you need to manually match them afterwards anyway. With my own Lumariver HDR you can pick one LCC shot as "anchor" (which would be the center LCC where there is the least color cast) to make sure all shots in a stitch get the exact same white balance, but I'm not sure if C1 has a corresponding feature. Maybe there are fixed presets?
    Torger: I have been thinking the same thing here (about the wb) so I can either take one of the 4 tungsten lamps I am using to light the painting and shine it directly at the LCC plate for the LCC shots, or simply replicate the whole thing back at the studio with a white card and perfectly even lighting, then apply there.
    Not sure which way I will go yet. Knowing me, probably all 3! Just to see which works best. The painting is way too large and too high up in the air to cover with white paper or sheet. But if I could that's what I would do.

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    Re: White Balance w/ LCC and C1

    Finished shoot of 14ftx11ft painting 25ft in air on scaffolding! All went well and pulled it off
    creating a 6 frame stitch using 80MP Credo 80 on Sinar P2 using sliding back. Almost 1.5GB file of incredible quality produced. (Layered file is over 4GB!)

    Even though the results are outstanding, the process was very tedious; and white balance, even using LCC corrections for each 16 sec exposure + gray card exposures helped smooth things....it required hours in photoshop.
    I will not do this method on the next one. I am investigating other solutions for this type of work including multistich back or getting away from 4x5/tech cam altogether and using DF and pan tools or rail system.
    Will start new thread about this experience soon with some pics.

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    Re: White Balance w/ LCC and C1

    Quote Originally Posted by Egor View Post
    and white balance
    A question/clarification, did you need to further tune the white balance when stitching inside photoshop? In other words, did the LCC procedure succeed to equalize the white balance 100%, or did the shots still differ a bit?

    I ask because I'm trying to write software that will make this type of workflows a bit easier.

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    Re: White Balance w/ LCC and C1

    Hi torger,
    Yes, white balance was not consistent.
    I believe it was due to competing color corrections between the LCC and the gray cards but there is so much going on in terms of shifting, cross polarizing, angles of incidence, individual lens behavior, sensor pixel crosstalk...that I can't see how to mathematically map it. I think if I can stay away from shifting within center of ic that would help greatly, talking to Myko at multi stitch about it now. Also trying a 15 ft rail xy platform for the DF camera and 120mm macro (my sharpest lens)
    Very interested in your efforts, though

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    Re: White Balance w/ LCC and C1

    I'd go for the rail. (or maybe just re-positioning the tripod) light falloff, lens distortion and color cast in the image circle will kill you if shifting and trying to match edges. a rotational pano would help, but you will change the geometry.

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    Re: White Balance w/ LCC and C1

    Torger: here is some idea of what we are dealing with. Look closely at the line going down center of this closeup where 2 of the 6 frames needed stitching. This is after LCC and gray card corrections. see it go yellow on left...blue on right? 3rd pick shows (loosely) the 6 frames needed to make the stitch.

    Trying to find time for new thread but takes time to get all the screen shots and writing.

    Jim, I am thinking of converting 2 rails from my high-glide system to be camera holders and connect them to encoders/servos
    Not easy task but do-able. The hard part is the programming of the computer control into C1
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    Re: White Balance w/ LCC and C1

    re-thinking it, if you set up the camera in three horizontal positions, you will have to control glare at each position. might be tough.
    given the forgiveness of stitching software, why do you need servos for positioning? seems like keeping square to the painting is the most critical, overlap less so

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    Re: White Balance w/ LCC and C1

    Jim, I think each solution is fraught with pros and cons, although I dont think glare will be much problem with cross polarized lighting. I will be more concerned with perspective issues related to 3-stitch flat with no center point, but wont know till I try. The eye is a funny thing and knows when it is being decieved by perspective. On the other hand, I dont think it will be an issue as the perspective will only be the viewer angle not the camera angle.

    Servos and positioning because I dont see myself getting up high enough to adjust camera position accurately and also, the math is easy once I plug in the xy coordinates, lens, and sensor size. But you are right, it can be done manually probably just as easily. All I have to do is convince my wife that its OK to have scaffolding built 25feet in the air and then carry a 12 foot step ladder up and set that up on top of that and then carry the gear....uhhhhh I dont think she's goin fer it. I'm gettin the hands on the hips deal

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    Re: White Balance w/ LCC and C1

    Thanks for the wb info.

    It does seem that Capture One lacks a mechanism to synchronize white balance modulation between LCCs, which makes stitching more cumbersome.

    This is not about the white balance in the image itself, but a reference white for the LCC shot, so the correction algorithm can know what in the LCC image that is color cast and what's neutral. Probably the C1 LCC algorithm derives this reference white from the LCC shot itself (averaging or something), and naturally when the LCC shots are not exactly the same the reference white will differ slightly, which means that LCC correction will modulate the white balance in the corrected images slightly. That is, even if you have the exact white balance settings on the LCC-corrected images, they still are slightly different.

    With Lumariver HDR I recently added the possibility to use one LCC shot as white reference anchor for all other LCC shots in a stitch (you pick the LCC shot for the center position). This make white balance stable. You still need to adjust exposure though, as LCC correction affects scaling somewhat. Could make an anchor for that too, but as everyone is using inexact Copal shutters anyway (ie exposure needs adjustment anyway) I have not yet seen a need for such a feature :-)

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