[frank]

Well, actually I can imagine that the vertical lines that are visible in the upper part of the image

are indeed artefacts of filterfunctions that were applied on the image. But without knowledge of

the type of postprocessing you did  this is like a look into the glas bowl.

 

If it wasn't there in the original (colored) image and it is there after postprocessing ...

odds are, it was caused by postprocessing.

 

Just my 2cts ... Rainer

 

 

Thanks, Rainer.

 

I applied the preset "low key 2" in Silver Efex Pro to the image, then I got the vertical lines. I tried other presets and found that once the brightness of the sky is turned down and the "structure" is turned up to certain amount, the vertical (and horizontal, though not as visible as vertical) lines showed up. 

 

I tried it with ACR 8.3 and did not find those lines. I assume that the "clarity" function in ACR is similar to the "structure" function in the Silver Efex Pro. It seems that CS6 does not have a function of "clarity" or "structure" otherwise I would apply it in CS6 after processing with the Silver Efex.

 

Frank