Remember the most important rule of Photoshop: never alter the original image.
Also remember the two basics about Photoshop Layer Masks: black hides, white reveals.
So how do you use a layer mask?
First you need a layer with an image on it that is not the background layer. Background layers are automatically locked, so we can’t alter them with a mask.
If you do want make the background of an image transparent (like if you want to import it into a layout in InDesign) you’ll need to cut out the object on a Background layer. To unlock the Background layer:
- double click on the background layer in the Layers palette
- click ok when the dialog box comes up
Now there is no Background layer, but instead a Layer 0 and the transparency grid (default is a white and light grey checkered pattern, which represents no pixel content) appears when you turn Layer 0 off (eyeball icon in the Layers palette).
Select the layer you want to add a Layer Mask to and click the Mask icon at the bottom of the layers palette. Unless you already have a selection, the mask will appear on the layer with everything revealed (white). If you have a selection when you click the Mask icon, then that area will be white while the rest will be black (hidden).
You can use many of the art tools on a mask, but it’s best to start out with the Brush tool. Later you can go in and Dodge, Burn, Blur, Sharpen, etc., if you need to.
Painting a Good Layer Mask
The key to a good Layer Mask is to match the brush to the pixel quality of the edge of the object being masked out.
With the Brush tool (shortcut is B), right click to bring up the brushes context-sensitive menu. All you will probably need is a normal round brush; it’s the Hardness attribute that really matters here. Test the edge of the brush to the edge of the object. Usually 0% or 100% are not ideal, I find somewhere between 65% and 85% to be good for most masking jobs.
Now you simply paint with black to hide and white to reveal! The great thing about masks is that if you hide too much, you can just switch to white (shortcut X) to paint a section back in.
Troubleshooting
If you can’t get part of the layer to disappear when you are painting in your Layer Mask, there are several things to check:
Are you painting with black? Look at your background and foreground color thumbnails and make sure the top one is black. Hit D to reset these to the default (white foreground, black background) then X to switch the foreground and background colors so that black is the foreground color. You will use X very often when masking, so it’s a good shortcut to memorize.
- Is the Mask selected? You have to click on the layer mask thumbnail in the Layers palette (see image).
- Are you sure you’re in the Brush tool? Hit B to make sure.
- Is the opacity of the Brush tool 100%?
Check the status in the context-sensitive toolbar at the top of the screen or hit 0 (zero) to change the opacity to 100%. The opacity shortcuts are another good set of shortcuts to learn (1=10%, 2=20%, etc).
Next, we’ll cover some expert techniques for using Photoshop Layer Masks. Be sure to subscribe to Creative Curio so you don’t miss it! An email subscription is available, too!
Photoshop Masking Series So Far
Good article! Works for GIMP too! Not sure whether there’s a hardness brush option – I might have to use a fuzzy brush or make a new one to get the right effect, but otherwise all good.
I’d be interested to see how you have used this to interesting effect. Maybe a post going through editing a photo. I’m thinking it would be good for editing a portrait where you want to soften skin, but sharpen hair and eyes. Good for landscapes too, the sky is often too bright for the land, but as you showed last post – it’s not always done well.
Kristarella,
Oh man, I use layer masks all the time… I’ll go over a few more ways to use Layer Masks tomorrow, including using a channel to make more precise masks. I’ll keep an eye out for when I’m working and using layer masks to edit a photo a lot. I use them with hue/sat to take the redness out of people’s faces quite often (mentioned in this post).
Yay! Glad this will work for GIMP
It’s funny you tend to alter the hardness of the brush from 65% to 85% whereas I always have the brush on either 0% or 100%, depending on the nature of the mask, and then sometimes alter the opacity of the brush.
Rob,
Yeah, I do 0% or 100% hardness, too, but I find myself using somewhere around 65-85% more often. Things rarely require 0% I’ve found. I like the on-the-fly opacity controls offered by the Wacom tablets. Do you have one?
No, I’m struggling along with the old mouse. I used to do a lot of work out at other people’s studios. Now that I’m on my own computer a lot I should think about getting on. It’s just the fear of the time is going to take getting used to it!
Rob,
A Wacom tablet does take some time to get used to, but I didn’t have too much of a problem with it. I did a review on two different tablets if you’re having a hard time deciding which is for you.
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