Suggestions need on night shot

tripwater

Tonight where I live there is a mist in the air. I came across a cemetery with a lit cross. I noticed across the street, a street lamp offered a dark orange contrast to the light blue of the cross. Almost like good and evil.

So I mounted it on a tripod. 1/13 sec at f2.8 ISO 100. Canon 50D with Tamron 90mm macro lens ( only lens I have at present )

I am happy with the shot itself but wondering what the deal is with the dithering rings around both lights fading into the blackness? I know that compressing a jpg will cause some of this but my raw file seems to have this to a lesser extent when viewing in Lightroom.

Any thoughts on how to avoid this or clean this up in post? I would really like for the light to fade into the darkness and not have dithering rings :P

Thanks

aaronbrown

tripwater wrote:

Tonight where I live there is a mist in the air. I came across a cemetery with a lit cross. I noticed across the street, a street lamp offered a dark orange contrast to the light blue of the cross. Almost like good and evil.

So I mounted it on a tripod. 1/13 sec at f2.8 ISO 100. Canon 50D with Tamron 90mm macro lens ( only lens I have at present )

I am happy with the shot itself but wondering what the deal is with the dithering rings around both lights fading into the blackness? I know that compressing a jpg will cause some of this but my raw file seems to have this to a lesser extent when viewing in Lightroom.

Any thoughts on how to avoid this or clean this up in post? I would really like for the light to fade into the darkness and not have dithering rings :P

Thanks

First off, awesome shot!

Looks like some banding...
Try masking in a layer of noise to help blend it out.

sgbotsford

Rings around bright objects
Your image on my screen doesn't show the dithering much.

However: Here's the problem:

A Jpeg image has 256 levels or about 8 stops. As of when I bought my Nikon detectors had a usable range of about 6 stops. The world we look at has a range of 4 to 12 stops.

Consider a dark image with a bright source. The blown highlight in a picture with
12 bit AD conversion will be recording a number of 4096. The merely pure color
with have 4095, and on down to to the blacks which will have random noise.

Now convert that to an image. Paper only has a range of about 9 stops.
So everything on the camera between some large number and 4095 gets mapped
to a single colour on output. Then there is a change. and some new color is used.

Or what the image making software does is try to create the intermediate color by using a dither pattern. In either case you get bands of dots.

These are present all the time. Every picture you take that uses full range of your camera + software + image presentaton. It just that in most pictures there is enough going on you don't notice. It becomes noticeable when you have bright
lights shading into a dark background with no texture on the dark background. Your eye tries to pull more info out of the pic and notices the faint dither rings.

Things you can try:

1. Start with raw.

2. Bring into photoshop or other high end post processor as raw image.

3. Use a more random dither such as floyd-steinberg

4. Use the processor software to drive the printer. (Most printers are really dumb
about dithering)

5. As someone else said, try adding some noise -- but work in LAB space and add
only to the luminance channel.


6. use Whisk! It's good for ring around the collar.

tripwater

sgbotsford wrote:

Your image on my screen doesn't show the dithering much.

However: Here's the problem:

A Jpeg image has 256 levels or about 8 stops. As of when I bought my Nikon detectors had a usable range of about 6 stops. The world we look at has a range of 4 to 12 stops.

Consider a dark image with a bright source. The blown highlight in a picture with
12 bit AD conversion will be recording a number of 4096. The merely pure color
with have 4095, and on down to to the blacks which will have random noise.

Now convert that to an image. Paper only has a range of about 9 stops.
So everything on the camera between some large number and 4095 gets mapped
to a single colour on output. Then there is a change. and some new color is used.

Or what the image making software does is try to create the intermediate color by using a dither pattern. In either case you get bands of dots.

These are present all the time. Every picture you take that uses full range of your camera + software + image presentaton. It just that in most pictures there is enough going on you don't notice. It becomes noticeable when you have bright
lights shading into a dark background with no texture on the dark background. Your eye tries to pull more info out of the pic and notices the faint dither rings.

Things you can try:

1. Start with raw.

2. Bring into photoshop or other high end post processor as raw image.

3. Use a more random dither such as floyd-steinberg

4. Use the processor software to drive the printer. (Most printers are really dumb
about dithering)

5. As someone else said, try adding some noise -- but work in LAB space and add
only to the luminance channel.


6. use Whisk! It's good for ring around the collar.

Thank you aaronbrown. Thank you also sgbotsford. I took raw files in my carmera and also imported into LR as raw. I use the highest quality I can. I still notice this effect even then. The jpegs I mention in my original post were the ones I exported for web to post here. I just wanted to avoid having someone tell me 'Well jpegs are compressed, and..."

I will try to fix this in post. Not real sure how to effectively add a noise layer in photoshop. I have never worked with noise layers. I know how to work with layers, just never one soley for the reason of helping noise. Thanks for the helpful advice! I will see what I can do.

tripwater

I would also like to say that so far, I am very pleased with the overall vibe of this forum. I am new and learning. As a newbie, I enjoy keeping things positive in the learning process in anything I do. I helps keep me motivated and not get discouraged. I signed up in another forum and pretty much get pretentious, arrogant replies on a regular basis.

I appreciate the fact that the people here so far have been courteous and helpful.

Thanks again.

aaronbrown

tripwater wrote:

I will try to fix this in post. Not real sure how to effectively add a noise layer in photoshop. I have never worked with noise layers. I know how to work with layers, just never one soley for the reason of helping noise. Thanks for the helpful advice! I will see what I can do.

No problem.

Here's a quick link I found in Google after searching "fix banding in ps":
http://www.graphics.com/modules.php?name=Sections&op=viewarticle&artid=371

I'm sure there are better out there, but this one seemed decent. Hope it helps. Sorry I don't have the time to detail it myself.

Dgrin has been such an awesome place for me to learn. I'm always happy to return the favor. Cheers!

pathfinder

Adding just a touch of Gaussian noise is a frequent means of dealing with banding in images.

Computer generated gradients are frequent sources of banding in digital editing - adding a small, non-visual amount of noise will usually solve the problem.


Copy your background layer with ctrl-J. Go to Filter -> Noise -> add Noise ( I think these commands are correct for PS but I do not have PS on my laptop at work ) . You can then use Edit->Fade, or you could paint back in the areas you do not want noise in with the History Brush.

Or you can create a new layer to put the noise into after filing it with a color similar to your image area with the noise, and use a mask to control where the noise is added in your final image. Adjusting the opacity slider will then be your final control of the degree of noise added.

Lots of ways to do this. I suspect you can even select the area of banding and run a denoise filter like Noiseware on it also. You can do this on a layer also, as that is how I do my de-noising generally.

And finally, does the banding even show up in a print? It may not.

BinaryFx

tripwater wrote:

Not real sure how to effectively add a noise layer in photoshop.

I have one method documented at my site

http://members.ozemail.com.au/~binaryfx/howto_smartnoise.html

The general idea is to "roll off" the effect into the extreme highlights and shadows so that pure black and white tones do not become "peppered".

That being said, I would do test prints if possible before introducing noise (or keep a layered version so that you could remove or reduce or re-do the noise if required).

P.S. Nice shot, I personally would like to see just a little bit of a hint of more foreground "detail" (outline, silhouette), that is very close to but not fully black.

Regards,


Stephen Marsh

members.ozemail.com.au/~binaryfx
prepression.blogspot.com