Vignette Banding?

[ShaneS]

I have experienced this a few times and need some help from you knowledgeable folks on what I might be doing wrong. I have created an image and wanted to put a fairly strong vignette on it but when I do I get horrible banding.

Here is what it looks like with the vignette:



The method to create the vignette was to create a new layer filled with black. Create a mask with the oval marquee tool and feather it 250px (I also tried feathering it more with the same result) . Opacity reduced to 25% and the layer is set to normal blend mode.

For reference here is the image without the vignette(I can't see any banding):




PS - This is was edited from a RAW file as a 16 bit image if that makes any difference.
Thanks in advance for any assistance.

[Dave Humphries]

Hi Shane,

I am struggling to see the issue in the example above, but in general .....

The kind of operation you performed is exactly the kind of thing that might be expected to show up issues when an 8 bit source file is manipulated.

It will help us to know exactly what software you are using. (?)

Also (assuming full Photoshop), was the image maintained as 16 bit when Opened from ACR in to PS?
(it is easy to accidentally/unknowingly convert to 8 bit if you don't have the correct option set in ACR)

In fact, to avoid overlooking something, it would be wise for you to give us a detailed (minimalist) workflow with which you can replicate the problem.

Thanks, Dave

[shreds]

No, I cant see any banding, either, just a gradual change from a bright centre to a vignetted outer.

[DanK]

It's very hard to see at this size and with the low resolution of a computer monitor, but I think I can see a slight curved banding. Is that what you mean?

[Manfred M]

Shane - it looks like a normal vignette to me as well, but I also feed that it is rather heavy, given the bright sky. When I vignette you generally wouldn't notice that there is one unless I either told you or showed you the before and after shots.

One place I am extremely careful with vignettes is scenes like the one you show, snow scenes, etc. where adding an element of gray is not going to help to composition. If fact in some snow scenes I use a reverse vignette (i.e. a white rather than black one).

[Mike Buckley]

I get far worse banding when working with a photo that has no vignette applied during post-processing but instead has the vignette created by my lighting setup in my makeshift studio. I'm convinced that it's due to the limitations of the 8-bit image information.

[ShaneS]

Sorry for the delay in responding but work got in the way of the detailed response that I wanted to give.

Dave, here is my minimalist work flow:

1 - Minimal adjustments in ACR - In fact I only reduced the highlights -3, did sharpening of the file (masking out the sky) and then took it into Photoshop CS6. The file was maintained as 16bit into CS6 and I can see the banding even before I convert the processed file to JPEG.

2 - Added a BW adjustment Layer, then a curves layer (a fairly classic s-curve) set to soft light blend mode.

3 - Added my vignette as stated above:

The method to create the vignette was to create a new layer filled with black. Create a mask with the oval marquee tool and feather it 250px (I also tried feathering it more with the same result) . Opacity reduced to 25% and the layer is set to normal blend mode.

I played with the opacity of the vignetted but there seemed to be some banding even at 5% opacity. There was not visible banding in the file before the vignette was added.

Having looked at this thread on my work monitor I think that part of my problem may be the monitor that I use at home (Samsung SyncMaster P2770) as the banding seemed less on my work monitor.

Dan - yes the curved banding is what I am trying to minimize.

Manfred - the strength of the vignette is an artistic choice that may not to be to everyone's liking but the issue at hand was not so much the vignette as the technical problem of how to mitigate the banding that I am getting in PP.

Mike - I thought it might be due to the conversion to JPEG (8bit) but I can see the banding before I make the conversion.

A search of the internet seems to indicate that I am not the only person experiencing this issue and the suggested ways of dealing with the issue range from adding noise to the vignette (not something that I wanted to do) and adding a Gaussian blur to the vignette which I tried but didn't seem to have a significant impact on the banding. I was hoping that the technical gurus here would have a fix...

Thanks to all for taking the time to comment.

[Manfred M]

Shane - as you see it more than we do, I suspect that your diagnosis is correct and you have an issue with the computer screen you are using. Unfortunately, the specs on the device are not terribly clear, but it is a normal gamut (sRGB) screen. Based on the price point, I suspect it uses 6 + 2 bit colour technology, i.e. it achieves the full sRGB range by dithering (which is a nice way of saying it cycles some of the pixels of and on quickly to emulate a the full range of colours it produces).

This all suggests that you likely have a display issue more than anything else and other than using a different display, there is no real solution to what you are seeing.

[Mike Buckley]

adding a Gaussian blur to the vignette which I tried but didn't seem to have a significant impact on the banding.

I've also had the same experience. Sometimes, adding Gaussian blur has made the banding appear worse though in a different sort of way that is typically not described as banding.

[dje]

Hi Shane

I can't see the banding much either but it is probably more visible on your full size image. Have you tried another method of producing the vignette? eg using the Lens Correction Filter in PS (or ACR). Even if it's not your preferred method, it may help to see just whether it is a particular method which is causing the banding. The Nik filter ColorEfex also has a vignette effect.

Dave

[xpatUSA]

I have experienced this a few times and need some help from you knowledgeable folks on what I might be doing wrong. I have created an image and wanted to put a fairly strong vignette on it but when I do I get horrible banding.

Here is what it looks like with the vignette:



The method to create the vignette was to create a new layer filled with black. Create a mask with the oval marquee tool and feather it 250px (I also tried feathering it more with the same result) . Opacity reduced to 25% and the layer is set to normal blend mode.

For reference here is the image without the vignette(I can't see any banding):




PS - This is was edited from a RAW file as a 16 bit image if that makes any difference.
Thanks in advance for any assistance.

Here's an ImageJ plot of the first image posted:



First I took a plot from the mountain peak directly upward to the top of the image. We see the upper plot showing an 'S' tonal curve with, not surprisingly, banding showing up in the upper and lower value areas. The lower plot is from just the bright area near the peak. again in an upward direction.

I am not an Adobe user, so have no precise answer. But those plateaux in the lower graph are up to 10px wide which is quite a lot for what is supposed to be a smooth gradient. At least you now have some idea of the magnitude of the issue

P.S. there is banding and noise in your original image which is hidden by the brightness of the sky, but is easily seen in an ImageJ plot. I was pointed to that when I tried to apply a vignette in RawTherapee (uses 32-bit floating point calcs) but got an output even worse than yours!

[ShaneS]

Thank you Dave & Ted. I will take a more detailed look at this over the weekend and reprocess to see if I can avoid the banding in the original process.