Aperture's toolset isn't always obvious at first glance. Especially to new users. One of these somewhat hidden features is part of the Print Window: the ability to build creative picture layouts. We're talking diptychs, triptychs, mosaics... Anything that doesn't overlap and can fit on a linear grid.
But what's even more interesting is the fact that this feature isn't restricted to prints: you can save the results back into any Project (as either JPEG or TIFF) thanks to the Save PDF to Aperture workflow. This is actually an Automator workflow which appears in OS X's universal print dialog (via the PDF Services folder in the main Library). You access it by clicking the PDF button:
As I said this appears in ALL print dialogs, meaning you can use this to save anything printable back to Aperture as an image: model release, field notes, whatev. Combined with metadata and stacks this can be powerful stuff. But back to those layouts...
The important thing to remember when using this method is that order matters — the pictures will appear in the layout from left to right in the order you selected them in Aperture's browser window. Doesn't matter how many images there are. And while you can change the size and positioning of each picture within its cell once you're in the print window, you cannot change this initial order. So you need to keep this in mind. For instance in the following example I wanted a colour image at each corner, so I calculated they needed to be selected as 1, 4, 13 and 16:
- Select the Standard preset.
- Click the gear icon at the bottom of the window and choose Duplicate Preset.
- Name your new Preset.
While I have quite a few saved layouts, I usually keep an "open" preset that I use for experimenting. Something I don't mind overwriting. My reason for this is Aperture's awkward method for saving these presets. Unlike anything else in OS X there's no Save As... If you plan on using a preset as a starting point you need to duplicate it first. If you don't you risk overwriting the original settings when you exit the print window since Aperture will ALWAYS ask you to save once you've made ANY changes. If you hit Duplicate after having made changes to an original preset, you'll have to save the new one and NOT save the old one... It's a bit too involved IMHO. With Save As a new preset is usually added while the original one remains untouched. One of Aperture idiosyncrasies I guess.
Once you've created your new preset make sure you hit the More Options button at the bottom of the window to reveal all the tools available. First and foremost you must change the number of rows and columns to match what you intend to do. Then, change the Photos per Page to reflect the number of images you've selected — they won't all be visible otherwise.
You can use Row/Columns Spacing and the Margins section to create your layout by entering values in the boxes, but I prefer dragging the borders visually — your mouse pointer becomes a two-headed arrow when you hover over a margin. I then use those boxes to refine the values. Here are a few examples of what can be achieved:
Another very important thing to remember: everything in the Print Window will affect the final PDF output. This means Colorsync, Image Adjustments, Borders... everything. This can of course be used creatively, but if you don't want any changes made to the images in the layout make sure you disable those settings, especially the Colorsync profile. Setting this to Printer Managed will effectively disable it altogether since in this case you won't be reaching the printer.
The Save PDF to Aperture workflow works in anything you can print, so you could also use Aperture's Book Tool or Light Table to create layouts. They each have strengths and limitations compared to this Print Window method. With the Book tool you first need to create a new size preset and clean up all the unnecessary page templates. With the Light Table you can't preview the size of the output, making it close to impossible to control the margins in the final image. That said: The Book tool can add styled text and offers much more control over the layout.
The Print Window's biggest advantage in my mind is speed: it's quick, dirty and works really well. The ability to manipulate the layout and to directly target a paper size (and by extension image ratio) makes it completely WYSIWYG.
And sometimes — not often — it's nice not having to fiddle about ;)