These are the set of instructions Linda Sharp sent to me, step by step.
This technique assumes a reasonable knowledge of Photoshop and layers. I don’t know if it will all apply in Elements as I haven’t tried.
The first step is to decide what sort of arrangement you want in terms of your images. My Triptychs tend to be 3 images each of the 2/3 ratio although I am currently experimenting with square images arranged in 4’s and letterbox images arranged vertically and horizontally. All good fun…
Once you have decided on your layout you need to create a blank canvas which will form the background to your image. The good news is that once you have created the canvas with all your correct measurements you can save this as a template and use it over and over again.
The blank canvas will take some measuring and you do need to be exact when creating the template so this can take time.
For example, if you would like a triptych which follows the same format as mine you would work with a ‘window’ of say 1500 pixels tall by 1000 pixels wide. Working in a landscape format you would need 3 windows horizontally. You will want a gap between each of say 50 pixels and an edge of the same, 50 pixels. You can now create your new blank canvas which would have dimensions of 3200 pixels (1000×3 + 50×4) horizontally by 1600 (1500 + 50×2) vertically.
Using the rulers (set to pixels rather than cm or inches – you set this in the Preferences) and guides (guides are dragged in from the edge of the rulers) you then need to mark out your windows by dragging the guides onto your canvas. This needs to be fairly accurate so zoom in quite closely so that you can see the rulers in enough detail
You should now have a background with a grid. The windows of the separate images would be marked out by the guides. Leave the guides visible when you save the file as these are the key to the next stage. This is the template complete now and you can save this and reuse.
You now need to work on your images and save them each individually. They don’t need to be in any special format. Mine are all working photoshop files and I don’t bother flattening them first as they are generally work-in-progress.
Go back to your canvas and follow the command File/Place and you will see an explore window which allows you to select one of your saved files. The selected file will appear in your triptych canvas with handles on each of the corners. Using the mouse, drag the corners into the template windows and the image should ‘snap’ to the guides. Press enter and the imported image will be saved to its own layer within your template. Do this for the other images and you have your triptych. You can then work on the images within the triptych, or work on the individual files and re-import as necessary until you are happy with your final arrangement.