Banding in dodge/burn layer

Hi, in CS6, when I create a dodge/burn grey layer, I notice some banding or posterization in the areas that are burned. Although it does not have any material effect on the final image, I am just wondering if there is some setting in CS6 that can be changed to reduce this banding? Thanks in advance for any inputs!

The first thing is to make sure you are working in 16-bit mode in CS6. It won't help much if you are editing Jpegs, which are only 8-bit, but if you started with a raw image that you developed as 16-bit you will be retaining maximum data for editing.

After that, I think the most common cause of banding when viewing the image on-screen is the monitor itself. This kind of banding will usually just impact the image as viewed and not the actual image data. Trying different setup options during calibration and profiling might help a little (like using native white point and gamma) but ultimately you may just be limited by the quality and technology of the monitor itself.

Another thing to be aware of is that digital camera images have fewer tonal steps for dark tones that for light ones. If you start to significantly increase the brightness of dark areas of an image, those tonal steps can start to become visible in the form of banding or posterization.

DO a simple experiment - in Photoshop make a new document with the same bit depth and color space your current document is using.

Fill the new document with a black-to-white gradient. First set the smoothness of the gradient at 0%.

DO you see banding and artifact in the shadows?

This is a consequence of your display. See Eyeball's comments above.

kirk

Do this experiment to see how banding varies depending on settings:

1. Create a blank white document, 1000 pixels square.
2. Put the document in 8 bit mode, any colorspace (colorspace does not matter).
3. Dupe the background 3 times (for total of 4 white layers) and turn all layers off.
4. Select a round brush, size 500px, hardness 0, color black.
5. Set the brush Opacity to 50% and the FLow to 100%.
6. Target and turn on the bottom layer (1).
7. Position the brush in the center and without moving it, left-click 16 times.
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8. Change the brush Opacity to 100% and the Flow to 50%.
9. Target and turn on Layer 2.
10. Position the brush in the center and without moving it, left-click 16 times.
11. Now display the image at 200% or 300% and pan around the edges to see the banding. Toggle the bottom two painted layers on and off to see the difference. Notice that 50% Flow creates less banding than 50% Opacity.
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12. Change the document to 16 bit.
13. Repeat steps 1 thru 11 using the top 2 layers.
14. Notice much less banding in 16 bit mode.

Summary: Brush painting in 16bit mode with reduced Flow (instead of reduced Opacity) is best. There may still be some banding, but far less than any other option.

Note: In older versions of Photoshop, the brushes (and gradients) operated in 8 bit mode even when the document was in 16 bit mode. I can't remember for sure, but I think it was CS3 and before. Starting with CS4 (or maybe CS5), the brushes operated in true 16bit mode and banding was reduced.

I'm guessing you were using a hard brush, even with reduced flow and opacity the hardness will carve out a furrow. Try setting it to 0 hardness and see if that cures it.

My display does this when showing masks (in 16bit), but after applying the mask the image is fine.

I actually never figured out if it was my display or something in PS (e.g. displaying masks in 8bit for speed), but either way since it doesn't appear in the image it doesn't bother me too much.

Thanks to all. I compared working in 8-bit and 16-bit and definitely the 16-bit has significantly less banding and is very smooth. One interesting point is that when I convert an image from 16 to 8 bit, the banding does not get worse i.e it stays as it was at 16-bit. When I change an image from 8 to 16 bit, the banding stays as bad as it was at 8-bit.

The other finding is when I save an image in jpeg, the file size remains the same whether at 8-bit or 16-bit.

There's no real final image quality difference when I work in 8-bit or 16-bit, although there is this banding in the burn/dodge mask. So, is there any real advantage in working in 16-bit compared to 8-bit? Hope so not, as my previous work were all in 8-bit.

mrmarks wrote in post #17220607
Thanks to all. I compared working in 8-bit and 16-bit and definitely the 16-bit has significantly less banding and is very smooth. One interesting point is that when I convert an image from 16 to 8 bit, the banding does not get worse i.e it stays as it was at 16-bit. When I change an image from 8 to 16 bit, the banding stays as bad as it was at 8-bit.

I'm not sure I can explain this well, but it is similar to processing a 16bit vs 8bit image. If you convert the raw to 8bit and do nothing it will probably look OK and very similar to a 16 bit file. However, if you take that 8bit file and start working on it, it can show banding where as the 16bit will not. Similarly, for many/most images if you send them to a printer or final output at 8bit AFTER all the adjustments, it will usually be hard to tell the difference between that and a 16bit output.

mrmarks wrote in post #17220607
The other finding is when I save an image in jpeg, the file size remains the same whether at 8-bit or 16-bit.

That is because .jpeg is 8-bit, which is why people prefer to work from the raw file and then convert to 16bit tiff to work on in PS. If using ACR and then directly opening up in PS you should set ACR to 16bit.

mrmarks wrote in post #17220607
There's no real final image quality difference when I work in 8-bit or 16-bit, although there is this banding in the burn/dodge mask. So, is there any real advantage in working in 16-bit compared to 8-bit? Hope so not, as my previous work were all in 8-bit.

Yes. Although with the adjustments you have done, or typically do there may be no obvious difference, the more you adjust, the more difference there will be.

8-bit only has 255 values per channel. Suppose I 'push' and 'pull' those values around, the I could create gaps for instance if I add contrast moving some values more than others and/or in opposite directions. With 16bit the adjustment is spread over many more values (65536) allowing for more severe adjustments before you'll notice any adverse affects.

As someone who does landscapes and does manipulate images (even though I try to make the final result look natural), this is one reason I stopped using gimp (and would not use Elements) because they only work in 8-bit. There is still a far amount you can do in 8-bit, but I'd end up making multiple raw conversions with various adjustments, saving to 8-bit and then blending them. Working in 16bit I can usually just make those local adjustments as I see fit.

Thanks for the explanation. Yes perhaps in my previous work, I did not push the adjustments far enough to see any issues. OK, I will from now on work in 16-bit, to be safe, then convert to 8-bit for the final.

I have also checked very closely if the banding that appears in the burn/dodge layer in my 8-bit images creates any tonal steps in the final image. Fortunately not. I wonder why.

Redcrown wrote in post #17219873
Summary: Brush painting in 16bit mode with reduced Flow (instead of reduced Opacity) is best. There may still be some banding, but far less than any other option.

I did not know this. I must admit I'm having some difficulty seeing the difference, but I will take your word for it.

I'm now off to investigate exactly the difference between flow and opacity. For some reason I never liked using reduced flow so always set it at 100%. Sometimes it seems to give uneven brush strokes - I think I was doing something else incorrectly, or not the setting I wanted.

EDIT Hmm, although I really dislike the 'airbrush' setting, I should experiment with reduced flow for certain brushing.

Not that I make use of this very often, Flow at less than 100% makes the density dependant on brush speed/number of strokes. So if you move the brush quickly or go over the same area agian the density can be different. If you need a large area with the same density, that requires multiple brush strokes to paint it, then you need to adjust the opacity. Using flow will likely get you an uneven finish.

Alan

The behavior of "Flow" depends on the "Airbrush" setting. That's the little on/off icon next to the Flow percentage box.

If the Airbrush is ON, then things like BigAl describes will happen. Density will vary depending on how long you old the left-click button down, or how fast/slow you make strokes. It's hard to control.

If the Airbrush is OFF, then the brush will behave "normally". Leave the Airbrush OFF unless you are an artist making a painting.

When the Brush tool is selected, typing a number on the keyboard will change the Opacity percentage. Typing shift-number will change the Flow percentage. Example: "Shift-5" will set the Flow to 50%.

If you want to paint a constant tone in an area by stroking and re-stroking over the same area just to expand the edges, consider setting both Opacity and Flow at 100%, but using a "Gray" brush. Pick a density from your Swatches Pallet (50% gray, 30% gray, etc.) and paint away. You won't get "build up" as you pass over areas already painted.