Parallel whitish lines in Grey sky

David Woodyatt

David Woodyatt

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Name
David Woodyatt
Edit My Images
Yes
I shot the below image the other day and I think I'm going to get the image printed to about an A3 size. As such I've been going over it to fully remove any blemishes that I can see.

I created the image by processing it as normal then using the brush to selectively de-saturate the rest of the image. I personally really love the image but I've found a problem that I don't know how to fix.

When I zoom in on the sky or turn the brightness of my screen right up I notice lots of parallel lines in the grey sky. At first I thought I could import it into photoshop then use a Gaussian blur to remove it but that didn't work.

First of all am I being over picky? is it visible to anyone else? An if so what do you think is the best way to remove it? My photoshop skills are very beginner so please take that into mind.

Thanks all for any help.

Monk by Dave Woodyatt, on Flickr
 
Are you looking at a JPEG? is so it is probably compression related, if not it could be your monitor. Computer files/monitors are digital and there are only so many colours that can be rendered, there has to be a point at which it steps from one value to another. Just as an example an RGB grey colour might be 128,128,128 and the next lighter grey would be 129,129,129 there is no value in between these two steps.
 
Ok that makes sense. So what would you recommend I do If I wanted to print it? Would it just be a case of exporting it at a specific ppi? I'm viewing the RAW image.
 
A3 isn't phenomenally large, and I think that somewhere around 300dpi is about as far as a human eye can differentiate (might be less).

How far are you pixel peeping? I cant see any lines when zoomed in at 400% in Photoshop.

What sort of monitor are you using?
 
David Woodyatt said:
Ok that makes sense. So what would you recommend I do If I wanted to print it? Would it just be a case of exporting it at a specific ppi? I'm viewing the RAW image.
Click to expand...
I would ignore PPI altogether. The printer will print the file you send. I don't know which camera you used but to use my 18 MP camera as an example, pictures are 5184 x 3456 pixels. A3 is 420 mm by 297 mm - in inches about 17 by 12. That will give you 304 (ish) PPI by 288 PPI which is plenty.

You are not viewing the RAW image - most software will not let you and if it did, the picture would be essentially green. You are looking at a post-conversion version of the image.
 
Im using my Macbook, It was shot on a Nikon D800 so 36mp. Maybe its screen calibration then, I just wanted to be sure. The main areas are in the centre to to left, or atlas they are on my screen .
 
I can only just see the issue you describe on this rubbish monitor. If it is banding then adding a little noise - say 1% - usually fixes it. Gaussian Blur usually exacerbates this kind of problem rather than fixing it.
However I can see all sorts of processing artefacts - most notable an odd rectangle around the monk, some weird halos around the fencing and some stripes in the sky, especially near the top.
Adding a curves layer and dragging the midpoint right down makes these much more obvious:

monk.jpg
 
Yes thats exactly what Im seeing, I had added noise correction in lightroom so may remove that and see what it does. Any idea whats its from?
 
The rectangle around the monk looks very much like your masking is off. Ditto the fencing, but the halos also look like you've boosted the tonal contrast - or clarity - too far. Be really cautious taking it above +5 (say) when there are smooth areas next to high contrast edges.

The banding looks like a mixture of jpeg compression and smoothing / blurring / excessive noise reduction - it's usually made worse by successive applications of curves or levels manipulations.

hth
 
Thanks very much, I'l probably take the image back to the start and watch more carefully the adjustments I'm applying.

Much appreciated
 
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