Dealing with masks and noise

I’d like to get some help with this because I really don’t understand what is going on. I have a colour image with a wide dynamic range. I do some basic adjustments in Lr including bringing down the exposure by one full stop. I then export the image into Ps. In Ps I use a midtone 1 mask to build some contrast (“s” curve). So, here’s where I get confused. I bring up the contrast by applying the mask+ contrast and magnify to 100% - no noise. I reduce the opacity of the mask - no noise. But when I mask the mask and paint with a black brush to reduce the added contrast in some areas, noise immediately starts happening. Even if I paint out with a black brush on the original midtone mask, I’m immediately getting noise. So, if I reduce the opacity of the entire mask there is no noise but if I paint out the effects of the mask there is noise. I really don’t understand how or why this is happening and how to avoid it. I’m hoping someone can explain what is happening and how I could better understand and approach this problem.

I will be curious to read the input because I have encountered similar when trying to reduce the effect of a Tony mask with a brush. Little speckles show up.

@Harley_Goldman - I sent my problem off to Sean Bagshaw and he had me send him screen shots. He found the whole thing mystifying. It turns out I just wasted his time. After I’d sent him three rounds of screen shots, I noticed that my brush had somehow been set to “Dissolve” instead of “Normal”. I haven’t a clue what Dissolve is (one setting below Normal) but I must have clicked on it by mistake, maybe after I’d been using “Overlay” to make a sky mask. Anyway, once I set things back to normal the problem naturally went away. Maybe that’s what happened to you, but I doubt it.

Thanks for the info. If I run into it again, I will definitely check my brush setting. It could well have been that.

This may have something to do with kind of banding from brush gradient (hardness set to 0) and a color space the image is being processed in. I also encountered some kind of noise / banding while watching image at full width / height, which is usually a result of Ps generating preview of the image. It usually goes away when viewing at 100% magnification, when Ps renders actual image and not some kind of preview.

I too have found that the Brush Tool and any gradient (Gradient layer or Gradient tool) can introduce banding if contrast is increased in the area where the gradient transitions. I can’t avoid the Brush tool, but I do tend to avoid gradients for tonal change as a result of this “perceived” problem. I blame it on gradients being 12-bit and this somehow causing issues with 16-bit images, but I’m really not sure. Whatever it is, gradients tend not to be as smooth as we assume they are.

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