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IQ160 tiling issue

torger

Active member
Only Phase One knows for sure... it's quite easy to get confused as tests go either this way or the other, so I cannot say for sure I'm describing things correctly. What I do know 100% certain is that the current C1 does under some circumstances introduce tile lines which are not there in the raw data, even before LCC. This must be classified as a bug in C1. It's harder to figure out exactly under which circumstances this occurs.

The calibration data embedded in the back (and raw file) should remove tiling to a very high degree, if your back is properly calibrated you should not have any problem in normal use. If you use a 645DF and only do typical image processing you probably never have any problems. However with technical wides tiling can get a little bit visible anyway (as the sensor changes behavior slightly with tech wides), and/or with super high contrast processing (as calibration cannot be 100% exact) and then you need to apply LCC or in some other way suppress tile lines.

Actually I do not know if C1's LCC algorithm does support tiling suppression (they store LCC in a compressed format, and if that means 2D blurring, it won't be good for tiling removal), or if there's a separate algorithm that suppress tile lines without LCC guidance. Both is possible.

The problems we've seen indicates that there is a tiling suppression algorithm in there, which currently is unstable and does mistakes now and then (depending on exactly what pixels that are along the tile lines, explaning why behavior is so confusing, ie works sometimes, fails sometimes). Adobe's DNG converter also have a tiling suppression algorithm (I've asked Adobe's developers), so it's not unlikely that C1 also has it.

Latest on tethered vs non-tethered is that it you can get the opposite behavior. To me this indicates that it's not about that, but simply about what exact pixels that are in the image, even if images are almost exactly the same there will be some pixel differences and if a tiling suppression algorithm is unstable it can throw it off on one image and not on the other.
 
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