If you have been using PBD for a while and tried overlays as a way of grouping pictures, you may be interested in creating your own overlays. In this tutorial I will spell out the necessary steps to create your own overlay. It is assumed that you are somewhat familiar with Photoshop.
Step 1: Setting the size of the overlay
The overlay is stored as a PSD file, mainly because it contains paths and a transparent background. While the overlay dimension (in pixels) does not have to fit a specific page width and height, it is somewhat important to make it large enough. In a typical use-case, the overlay should not be have to enlarged more than, say, 50%.
We will start by creating a new document in Photoshop: 30×30 cm, 300 dpi, sRGB and with a transparent background:
In this case I named the document “overlay-white-VV-VV” because I intend to make an overlay for four Vertical photos with a white background, as seen below.
Once you click OK you should verify that the color profile of your document is sRGB, if you are creating a template for PBD.
Step 2: Creating the holes
Start by filling the document with white. You can do this either by resetting Photoshop’s background and foreground colors (press ‘D’) and then hitting cmd-Backspace (ctrl-Backspace on a PC). Or you can do Edit>Fill and fill the document with white paint.
In this template I want to create four holes, each one holding a vertical photo with 2:3 aspect ratio. Since the overlay itself is 30×30 cm I choose to make my holes 12 cm tall and 8 cm wide.
The marquee tool is useful for this job if you set it to a fixed size (see above settings). I can then click in my document where my first hole is going to be. Don’t worry about the exact placement – just make a rough guess and you can center the holes later by cropping and extending the canvas. After you have made your selection, create a path by clicking on “Make work path from selection” in the Paths palette (see right). 
A new path called “Work path” is created. Rename it “V01” by double-clicking on the name “Work path”. This path is used by PBD to figure out where the photos are going to appear.
Once you have the path stored it is easy to get the selection back: right-click on “V01” and choose “Make selection”. Set the feather value to 0 and press OK. Now you can cut out the hole by doing Edit>Cut:
There is normally some sort of border associated with the hole. In this example I will create a very simple frame by again getting my selection back from the path (right-click on “V01” in the Paths palette, remember?) and doing Edit>Stroke with a 10px black border, outside stroke. You can make arbitrarily sophisticated borders of course – they are just pixel patterns around a hole – but I recommend you practice with some simple overlays first.
Finally de-select (cmd-D or ctrl-D on the PC) so that you can make a new selection for the next hole. Repeat the same procedure again:
- Marquee tool with a fixed size to specify the position of the hole.
- Make a work path from the selection.
- Rename the work path to V01 or V02, etc.
- Get the selection back by right-clicking on the path
- Edit>Cut
- Get the selection back
- Edit>Stroke
- Select>Deselect
When the Marquee tool is active (press M if not) you can drag your selection to line up your holes perfectly. Remember that you can zoom in really close to make sure the holes are aligned.
After having created the four holes, paths and frames you should have something looking like this:
And there should be four paths: V1, V2, V3 and V4 (see right).
Step 3: Final touches
As you can see above, the holes aren’t centered on the document. We can quickly fix that:
- Select the crop tool and set the dimensions to 30×30 cm:
- Drag the mouse over the document to cover the largest area possible.
- Let go of the mouse. You can now drag the corners so that the holes are centered. Hit Enter when ready.
- Since the background is transparent, Photoshop added transparent areas around to extend the canvas. You can just fill these areas with white paint using the paint bucket tool (G).
- Finally, save the document in the folder where all your other overlays are stored. (It’s actually a good idea to do this once in a while during the design if you screw up or if Photoshop crashes.)
I have provided this particular overlay so you can download it from http://www.pixbookdesign.com/upload/overlay-white-VV-VV.psd
Step 4: Trying it out
Let us try the overlay. Create a new page spread in PBD and add four images:
Select all four images, click on “Add overlay”, choose your new overlay, sit back and… wham!
The “Add overlay” action, by default, places the overlay to minimize the movement of the photos but you can simply click on “Fill left page” and get the desired result:
It is also easy to open the overlay in Photoshop again, invert the document (Image>Adjustments>Invert), save it as “overlay-black-VV-VV.psd” and use it as such:
Finally
Good luck with your overlays but expect to practice a few times until you get it right. Remember that it is the path that defines where the photo is going to appear and the transparent hole controls what part of it can be seen. If you want to get sophisticated, you can try non-rectangular holes. If you create an interesting or useful overlay, or have some other good ideas, let me know and maybe we can start a library of contributed overlays.