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Thread: Tiling - how to remove in post?

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    Senior Member Pemihan's Avatar
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    Tiling - how to remove in post?

    As I do most of my work in B&W I often experience the dreaded tiling issue.

    The more contrast I use the worse it gets, so I have adjusted my PP style a bit which helps but never the less it sticks it's ugly head up.

    I shoot with a IQ160 on tech cam with Rodie 40HR, SK60XL and SK120 ASPH and of course use LCC and C1 to process the RAW's. I tested a number of backs before my purchase and this was by far the best in this regard and according to Phase One it is completely within spec.

    Sometimes I can remove the tiling lines by using the spot healing brush in Photoshop (CS6) but not always.

    Anyone else has this issue and an easy way to get rid of it in PP?

    Here's a 100% crop showing the issue. I'll be happy to supply the RAW of the B&W TIFF if anyone wants to experiment with it.

    Last edited by Pemihan; 16th October 2014 at 04:05.
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    Re: Tiling - how to remove in post?

    I always take LCC shots in the field and in most cases tiling is removed after LCC correction.

    Occasionally LCC does not fully correct tiling. I would refrain from applying heavy local contrast in the tiling areas.

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    Senior Member Pemihan's Avatar
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    Re: Tiling - how to remove in post?

    About LCC, what would be best in regard to tiling removal; shoot with the histogram all the way to the right or more in the middel?
    Last edited by Pemihan; 16th October 2014 at 04:00.
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    Re: Tiling - how to remove in post?

    Wasn't it the case that Lightroom (and hence Camera raw) handle tiling differently than C1 ? So for the "hard" cases, it might be useful to give LR a go...

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    Re: Tiling - how to remove in post?

    My experience is that the LCC shot would work best if it is taken under the same light condition as the photo.

    For example, if the LCC shot is taken when the sun is hidden behind the cloud but the photo is taken when the sun is directly casting to the camera then the LCC may fail to remove the tiling.

    Usually I take the LCC shot with +2 stops exposure compared against the photo (aiming for a perfect histogram for the LCC shot). The exposure of the LCC shot does not seem to affect the quality of correction if it is not overexposed or underexposed.

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    Re: Tiling - how to remove in post?

    Quote Originally Posted by miska View Post
    Wasn't it the case that Lightroom (and hence Camera raw) handle tiling differently than C1 ? So for the "hard" cases, it might be useful to give LR a go...
    Tiling is a physics problem with the sensors. There are partitions on the sensor and the borders of these partitions would result in discrepancy of exposure.

    Actually even the D800E and the IQ250 also have the tiling issue (divided by a vertical line in the middle), but only if you push them by abusing the image in post-processing to the extreme.

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    Senior Member Pemihan's Avatar
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    Re: Tiling - how to remove in post?

    Quote Originally Posted by voidshatter View Post
    My experience is that the LCC shot would work best if it is taken under the same light condition as the photo.

    For example, if the LCC shot is taken when the sun is hidden behind the cloud but the photo is taken when the sun is directly casting to the camera then the LCC may fail to remove the tiling.

    Usually I take the LCC shot with +2 stops exposure compared against the photo (aiming for a perfect histogram for the LCC shot). The exposure of the LCC shot does not seem to affect the quality of correction if it is not overexposed or underexposed.
    I always shoot the LCC right after the actual image is shot with +1 or +2 stops exposure..
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    Re: Tiling - how to remove in post?

    Quote Originally Posted by miska View Post
    Wasn't it the case that Lightroom (and hence Camera raw) handle tiling differently than C1 ? So for the "hard" cases, it might be useful to give LR a go...
    Yes in some instances and in some not. Also the LCC feature in Lightroom has a bit to be desired IMO..
    Peter
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    Re: Tiling - how to remove in post?

    CC content aware is your friend with sky tiling. The latest version of the LR spot healing brush can also sometime work.

    I am curious have you contacted Phase One to see about a re-calibration? Sometimes your calibration file on the back needs to be redone.

    I believe this is something that can be done by the dealer if you send them the file to calibrate. It depends on the severity of the tiling.


    One huge advantage to the IQ250. I don't believe it has the read outs which break the sensor readout into the 8 sections. I realize it's still one big sensor but the readouts on the Dalsa sensors create the issue since one section is reading different light data than the other creating the line. I believe it's a speed issue.

    I had to have my 269 calibrated a couple of times. And the calibration seems to be something that has to be refreshed every once in a while.

    The lenses you are less prone to cause the issue i.e. Rodenstock

    Paul

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    Re: Tiling - how to remove in post?

    Quote Originally Posted by Paul2660 View Post
    CC content aware is your friend with sky tiling. The latest version of the LR spot healing brush can also sometime work.

    I am curious have you contacted Phase One to see about a re-calibration? Sometimes your calibration file on the back needs to be redone.

    I believe this is something that can be done by the dealer if you send them the file to calibrate. It depends on the severity of the tiling.


    One huge advantage to the IQ250. I don't believe it has the read outs which break the sensor readout into the 8 sections. I realize it's still one big sensor but the readouts on the Dalsa sensors create the issue since one section is reading different light data than the other creating the line. I believe it's a speed issue.

    I had to have my 269 calibrated a couple of times. And the calibration seems to be something that has to be refreshed every once in a while.

    The lenses you are less prone to cause the issue i.e. Rodenstock

    Paul
    The IQ250 (and also the D800/E/810/A7R) has readout in 2 sections (left and right). It is just a lot harder to notice in real world usage. This can easily be observed if you take a darkframe shot of 1-hour long exposure and pull +5 ev in post-processing.

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    Re: Tiling - how to remove in post?

    Tiling issue gets worse with wide angles as the different responses of the tiles get exaggerated. It's not only about readout channels, it's also about how the sensor is manufactured in multilpe exposures. If you hold up the sensor towards the light and look at an angle you can actually see the tiles.

    In theory the LCC shot would cancel out the tiling, but only if it would have the exact same color that triggers the exact same response, which of course is not really possible. Probably as recommended above shooting an LCC under the same light will help a bit.

    By some reason unknown to me Kodak sensors (22, 39 and 50 megapixels) don't have tiling, or if they have it's extremely hard to reproduce. There's something different in the manufacturing process. They're more noisy though which is a disadvantage in high contrast processing so I don't know if it would actually work any better overall. It would have been interesting to see how a Hasselblad CFV-50/H3DII-50/H4D-50/H5D-50 shot would live through your B&W processing though...

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    Re: Tiling - how to remove in post?

    Quote Originally Posted by Paul2660 View Post
    CC content aware is your friend with sky tiling.

    I am curious have you contacted Phase One to see about a re-calibration? Sometimes your calibration file on the back needs to be redone.

    Paul
    Yes according to Phase One it is within spec and there's even a chance a recalibration can make it worse.
    The first IQ160 I got was horrible regarding tiling and I got it exchanged and got to try a number of backs and choose the best..
    But never the less the issue comes up once in a while.

    And yes content aware is so far the best solution I have found. Another method is to apply a adjustment layer on one side of the tiling line and adjust the exposure just a litte - around +/- 0.06 stop but I find it really hard to be precise enough.
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    Re: Tiling - how to remove in post?

    Quote Originally Posted by torger View Post

    By some reason unknown to me Kodak sensors (22, 39 and 50 megapixels) don't have tiling, or if they have it's extremely hard to reproduce. There's something different in the manufacturing process. They're more noisy though which is a disadvantage in high contrast processing so I don't know if it would actually work any better overall. It would have been interesting to see how a Hasselblad CFV-50/H3DII-50/H4D-50/H5D-50 shot would live through your B&W processing though...
    As far as I know the Kodak sensors only have one read out channel, hence eliminating the problem.
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    Re: Tiling - how to remove in post?

    Quote Originally Posted by Pemihan View Post
    As far as I know the Kodak sensors only have one read out channel, hence eliminating the problem.
    Yes, but there's more tiles than readout channels. An IQ160 has 8 tiles, if the sensor is horizontally you have one horizontal line and three vertical splitting the sensor into 8 tiles. The calibration data in the IIQ file address two things, there's amplifier curves per quadrant (which should be the readout channels and there are four), and there's also flat-field adjustments for those 8 tiles.

    The 8 tiles is what I think you can see physically on the sensor, and I think comes from the multi-exposure manufacturing process, and probably the response of the sensor will differ a tiny little bit between those tiles.

    Here's a picture I found of an Aptus-II 12, it's the 80 megapixel sensor which too has 8 tiles. If you look carefully you can see the tiles on the sensor itself:

    http://cdn.photigy.com/wp-content/up...gital-back.jpg

    And here's an image of a H5D-50 sensor:

    https://captureintegration.com/wp-co...271-0050-1.jpg

    no visible tiles there... could be the light though. Haven't seen one in person.

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    Re: Tiling - how to remove in post?

    Quote Originally Posted by Pemihan View Post
    Yes according to Phase One it is within spec and there's even a chance a recalibration can make it worse.
    The first IQ160 I got was horrible regarding tiling and I got it exchanged and got to try a number of backs and choose the best..
    But never the less the issue comes up once in a while.

    And yes content aware is so far the best solution I have found. Another method is to apply a adjustment layer on one side of the tiling line and adjust the exposure just a litte - around +/- 0.06 stop but I find it really hard to be precise enough.
    That's a great idea, I never thought of but it would be so easy to implement. Your B&W will be the worse case scenario to show it. I will sometime catch a tiling line in a shot I had printed in color and did not see it, but when I convert to B&W, there is is.

    I also found for some reason it may be easier to clear them up when in color, not B&W as Content Aware just works better in color, at least from what I have found.

    What's always scary, is on any shoot, when you look at the LCCs on the back or surface pro before being processed, almost always you see a tiling line, but once opened in C1 and processed all this goes away most of the time, but it always used to bug me in the field.

    Paul

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    Re: Tiling - how to remove in post?

    One other note, as I just caught this last month, using a CL-PL and shifting will seemingly make this problem (tiling) worse, especially on shifts. ND filters by themselves don't in my experience.

    Since I moved to the IQ backs, I find I just don't need a CL-PL for my sky as the color is just great by itself. However the CL-PL still helps on the green leaves and fall colors on leaves depending on the angle you are to them. So I will often bracket CL-PL on and off, as my sky will be most times just better without it.

    I still tend to use the CL-PL with all water shots as nothing I have found cuts the glare better.

    Paul

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    Re: Tiling - how to remove in post?

    Quote Originally Posted by Paul2660 View Post
    What's always scary, is on any shoot, when you look at the LCCs on the back or surface pro before being processed, almost always you see a tiling line, but once opened in C1 and processed all this goes away most of the time, but it always used to bug me in the field.
    It's there in the file, but as C1 knows where the tile lines are it has algorithms to further suppress the tile line even after LCC has been applied, same counts for microlens ripple. Great quality is had out of these Dalsa sensors but I as a multi-software user is not very fond of artifacts that require targeted product-specific algorithms to clean up. That's why I'm more and more looking in the Kodak direction despite that it's an older and in many other aspects less capable sensor...

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