Sky Color Banding

[rodpacker1]

Hi,

I am unable to resolve an issue with color banding in the sky.



I have viewed this on various monitors so it is not a monitor issue. It appears to be the glow that is causing the banding. I have tried increasing atmosphere samples from 16 to 256 and the result has no improvement and increasing the detail does not help either. My sample jitter has not been reduced from the default of 1.

From what I have read, it seems this used to be an issue with older versions of Terragen and increasing the atmospheric accuracy apparently helps, however this does not seem to be an available parameter in TG2.

I am running TG2 Deep Animation, 1.10.231

Thanks in advance for any assistance.
Sam.

[Kevin F]

sorry but on my monitor there's no banding at all!

[jo]

Hi,

I can see it in two monitors. Not sure what the problem is though.

Regards,

Jo

[Mohawk20]

Are you sure it's not due to jpg compression? Your file is awfully small!

[rodpacker1]

Thanks for the replys. It is just as visible with the uncompressed tif which was rendered prior to converting to jpg for the forum.

Are there any quality settings you could recommend which may improve the banding? I do have atmospheric shadows switched off, but can't imagine that would be causing any issues.

I assume this artifact could at least be dimmed in comp? If so any suggestions of color operations?

Cheers,
Sam.

[buzzzzz1]

No banding here either?  Do you have adobe Gamma on your computer? If so it should show up in Control Panel where you can launch it and run Gamma Adjustments. Of course you may already know this?  Just a thought. 

[cyphyr]

Nope cant see any banding here either. All I can think of is there might be some setting in your monitor config.
Richard

[Volker Harun]

Or your machine is set to 16bit-colours?

[Oshyan]

Two thoughts come to mind.

First, it's possible that the color gradients are simply too gradual for 24 bit color to represent it without banding. For example if you had a purely blue sky, with no elements of other colors, in 24 bit color space you would have only 256 shades of blue. Let's say your sky consists of only a portion of the blue spectrum, then you would have even less, perhaps only 32 or 64. If your sky gradient covers a large enough area this could easily be visible. The simple reality is that there is no way to get around this in 24bit color space besides using dithering, which TG2 does not do. The problem should be resolved by outputting in EXR however.

The second possibility, though I guess it more unlikely given the evident consideration and testing time you have given this, is that your monitor - likely an LCD - is simply not capable of displaying subtle gradients properly. This is true of many, many monitors these days, unfortunately. Only expensive, high-end monitors designed for color accuracy can show close to the true 16.7 million colors of the 24 bit color spectrum.

A bit more info here: http://en.wikipedia.org/wiki/Color_depth#LCD_displays

So I would ultimately try saving to EXR and examining the file in an HDR-capable image viewer. You may still be limited by the capabilities of your output device at that point, but you may also be able to downsample to a 24 bit color space using dithering...

- Oshyan

[trailgirl]

I have the same problem on my monitor. I can see the banding very distinctly, especially on the right of the picture, above the mountains. I have an iMac 15" 1440x900 32-bit. I often have banding in my tgd renders, I have tried many settings in Terragen, as well as recalibrating my monitor, changing the gamma, saving as .exr, etc. I would like to be able to fix the banding in Photoshop if it is a piece that is going on my website which will be viewed by visitors with varying quality monitors but I haven't figured that out yet (tried gaussian blur). BTW if I print out on my inkjet it appears as a beautiful continuous tone like a photograph, on both plain paper and photo quality paper.

[Oshyan]

I believe the lower-end iMacs do have limited LCD screens, so the banding in that case is probably due to limitations of your screen.

- Oshyan

[rodpacker1]

Thanks Oshyan,

Rendering out exr's reduced the visible banding on all of my monitors considerably!

It is still barely visible though and if this is a software issue it would be nice to have this resolved in a later release. Otherwise I can understand if this is simply due to the bit depth limitations of my LCD's, although I have tried quite a range now and it is always still just slightly visible.

Thanks again for your input,
Sam.

[Oshyan]

The way to avoid this would be some kind of built-in dithering or more random atmosphere sampling I suppose. I don't think values for sample jitter in the atmosphere quality tab above 1 do anything, but you *might* try values above 1 on a small crop area to see if it helps.

- Oshyan

[mt_sabao]

i was facing the same problem, but saving the file in exr, and then in phoshop adding noise, with extremelly low scale (0.1%, monocromatic, uniform), solved the banding. it completely took it away.
try it