how do prevent these arcs appearing: This picture looked great on lightroom in raw but when I converted it to JPEG I noticed these dirty looking concentric arcs in the sky. I remember...

drydock Loc: mackay, queensland australia

This picture looked great on lightroom in raw but when I converted it to JPEG I noticed these dirty looking concentric arcs in the sky. I remember vaguely that is is a software problem that occurs in the conversion process (something about 16 bit???). How do I prevent this happening please

drydock Loc: mackay, queensland australia

Correction, I've just had a good look at the lightroom pics and the arcs are in the RAW version as well-- they have become more noticeable on the JPEG version

drydock Loc: mackay, queensland australia

Update no 2. Just uploaded the pics to Iphoto. and can see the same marks, although not as prominent. Is this a sensor or lens fault or still a software fault??

drydock Loc: mackay, queensland australia

All the pictures I took today showing some sky show similar marks. I recall seeing this before on a couple of my earlier pics taken a couple of weeks ago, but I thought is was my laptop screen-- but it isn't.

Searcher Loc: Kent, England

Have you got a filter of any kind fitted to the lens?

CaptainC Loc: Colorado, south of Denver

It is a bit-depth issue. I am surprised they show up in the RAW file, however. Is your RAW file a 12-bit or 14-bit.? Although even the 12-bit should show a smooth tonal transition.

The issue is this: there is not enough data for the file to render a smooth transition -not enough blues, so there are jumps in the color. Converting to JPG will make it worse - or make it show up in the first place.

Are you SURE you were looking at the OOC raw file and not one that has had any processing done?

drydock Loc: mackay, queensland australia

16 bit raw file imported into lightroom with minor presets. I have a UV filter on the lens-- it looks clean to me. I did notice that on the lightroom settings the colour space was set to ProPhoto RGB rather than sRGB Would that have made any difference?

CaptainC Loc: Colorado, south of Denver

drydock wrote:

16 bit raw file imported into lightroom with minor presets. I have a UV filter on the lens-- it looks clean to me. I did notice that on the lightroom settings the colour space was set to ProPhoto RGB rather than sRGB Would that have made any difference?

ProPhoto is the LR default and is a MUCH wider color space, so that is not a problem. UV filter should have not effect.

I am not a big fan of LR (for my work), so I am not claiming any expertise, but do you still have the original raw file on the card and can you re-import with NO presets?

Dinah Loc: Brisbane, Australia

drydock wrote:

This picture looked great on lightroom in raw but when I converted it to JPEG I noticed these dirty looking concentric arcs in the sky. I remember vaguely that is is a software problem that occurs in the conversion process (something about 16 bit???). How do I prevent this happening please

As a matter of interest, would a program like Dfine 2.0 help to smooth out those lines? Anyone know?

drydock Loc: mackay, queensland australia

CaptainC wrote:

quote=drydock 16 bit raw file imported into light... (show quote)

Panic over!! In the cold light of day, I noticed that the marks on the RAW images stayed static when I zoomed up the images and moved the zoomed image around-- ergo, it was on the screen. I cleaned off the screen thoroughly and cured the problem.
Re the JPEG images however, these marks are truly on the image. Is the cure for this problem to simply make bigger JPEG files or to reduce the RAW file to 8 bit colour?

Nikonian72 Loc: Chico CA

drydock wrote:

Re the JPEG images however, these marks are truly on the image. Is the cure for this problem to simply make bigger JPEG files or to reduce the RAW file to 8 bit colour?

I believe these "arcs" are caused by sharpening when a large area has a subtle color change from one end to the other. If you intentionally over-sharpen, you should see an exaggeration of symptom.

Any JPG that you view, has someone's tweaking already applied, such as slight sharpening.

abc1234 Loc: Elk Grove Village, Illinois

CaptainC wrote:

...I am not a big fan of LR (for my work)...

What do you use then?

Lucian Loc: From Wales, living in Ohio

You can choose the sky area, make a layer mask and do a very subtle gaussian blur in Photoshop and then paint back in all the areas as it was except the sky area that is getting the banding, to help out your situation if nothing else helps.

PhotoArtsLA Loc: Boynton Beach

Ah, the Canon banding issue. Chances are, if you critically review the RAW file, it probably bands. This is partly bit depth, but also, possibly the Canon internal processing. Gradated blue skies are the perfect subject to reveal this problem.

A few years back I shot with the current top of the line Canon digital, and the RAW files banded on gradations. I even quit the PPA because they PRINTED Canon banding on their cover, apparently considering it normal. That spells a-m-a-t-e-u-r in the workaday professional world.

Gaussian blur will not truly fix banding, it might add to it. Classically, it is a combination of adding noise and sometimes blur of various types to fix it. For print, just adding noise is the fix. This has been true since the invention of drum scanners back in the film days.

Lucian Loc: From Wales, living in Ohio

yes, adding noise slightly in the sky area where the banding occurs will also do the trick.