This short article describes a Photoshop tip for refining a layer mask using an additional layer filled with 50% gray. It is assumed that you are already familiar with layers and layer masks.

Photoshop layer masks have become a very important part of my image workflow. Especially with wildlife shots where I'm fighting the effects of noise due to using high ISO settings in order to maintain fast shutter speeds. I don't typically want to apply noise reduction to the entire image because too much detail is lost in the subject, but with an out-of-focus background losing detail is perfectly okay. So, in a case like this, a layer mask can be used on the layer where the noise has been reduced. The mask is painted to show only areas where you want to see the noise reduced.

If you have ever used layer masks, you know how difficult it is to tell where you have and have not painted in the mask. In a case like noise reduction where you are acting on a copy of the image (it should be a copy, otherwise this method won't work), you can turn off the origianl image layer which sits below the working layer. This allows you to see each brush stroke where you are painting becasue a portion of the image disappears.

From the above image, it appears we have a layer mask that works really well. You don't see any artifacts from the use of the brush tool with missed areas. With this method I was fairly confident that I had created a good working layer mask. However, I had an occasion where I created a 50% gray layer below a noise reduction layer and noticed how poorly my brush strokes had actually been. Mind you, this was by accident that I could see all of these brush stroke artifacts, thus discovering another step needed in my workflow.

With this gray layer turned on, I was able to go back to the noise layer and do more painting on the mask to improve it. This has now become a standard practice for painting layer masks. To make the brush stroke artifacts stand out more, you can make the layer a darker gray. You might even want to create an action for this step to save a little bit of repetitive movement as well as time.

Once the layer mask has been re-touched, the gray layer can be turned off (what I do) or deleted altogether since it is a temporary tool for improving the mask. Now you're ready to continue with any other adjustments the image needs.

Why, you ask, is this a big deal? For what you are seeing here on this web site, it makes no visible difference. And, you could argue that it probably makes no difference in small prints. But in cases where I'm making strong adjustments such as noise reduction, I want to make every effort to preserve as much detail as I possibly can. In larger prints lost detail becomes more evident. This method helps me to preserve that detail.

As an aside to this tip, here's another one - if you do as much layer mask painting as I do and you are using a mouse to do all your painting, do yourself a favor and get a Wacom touch sensitive tablet. Your accuracy will go up and your frustration level will go down. I use the Wacom Bamboo CTH460 model. It has a 3.5" x 6" active area. There are larger models, which I'm sure give better control, but the trade-off is that they require more real estate on the desktop and they are a lot more expensive. This one is very economical and well worth the investment.

In addition to these devices providing a more natural approach to painting, they are also pressure sensitive so you can apply more or less pressure to affect the strength of each stroke. This becomes more apparent when you are using a feathered brush - it affects how much feathering is applied. There is a reason these devices were invented and still in popular use.

Happy painting!

• Wacom