Derek Lea reveals ways to make compositing layers using layer masks, vector masks and alpha channels a doddle.
Add masks to groups
In Photoshop, each layer can have a single layer mask and a single vector mask. However, if you place a bunch of masked layers inside a group, you can add additional masks to the group. You can then edit the group’s masks without affecting the masks of individual layers. To take this even further, you can put this group within another group, add that to another group and so on, masking each group individually.
Mix your masks
As each Photoshop layer is allowed two masks, using them in conjunction with each other gives greater versatility. Use a vector mask to mask sharp areas and a standard mask for regions that require a softer approach. You can edit either mask at any point without affecting the other.
Fill layers are better
When building up regions of colour on a series of layers, use Solid Color fill layers rather than standard layers. You can easily define regions by editing the layer masks. Also, you can change the fill colour of a Solid Color layer at any point by double-clicking it. This non-linear approach lends itself to the intuitive back-and-forth nature of the creative process.
Swap black for white
When creating alpha-channel-based selections in black-and-white artwork, try inverting the colour indication to Selected Areas in the Channel Options (accessed via the Channels panel menu). This will result in selections based upon black areas (ie usually the drawings) rather than white (the backgrounds). You can then fill these selections with colour on a series of layers or, even better, use these selections to mask a series of Solid Color fill layers.
Photoshop’s adjustment layers can be applied in a targeted way rather than image-wide. To make an adjustment to a specific layer-based component only, Cmd/Ctrl-click its layer thumbnail – this will load it as a selection. Creating an adjustment layer then affects only the selected region as a mask will be automatically created, excluding the adjustment from areas outside the selection.
Derek Lea is an award-winning illustrator and acclaimed author based in Toronto, Canada. His latest book is Beyond Photoshop, beyondphotoshopbook.com