Border question for print project.

I'm working on a project where I'm going to put a bunch of prints on my wall. 24 prints wide, 12 prints tall... each of the 288 prints measuring 4x6. They were taken with a variety of cameras (Canon powershot A85, rebel xt, 40D, 7D)... and I've cropped some, so resolutions are all over the place. Everything is edited and cropped to a 4x6 size (using Lightroom 3).

What makes this an interesting project (to me) is that each print will have a thin white border. That will make all the images uniform, and give the wall a nice, even, grid look.

My question is in regards to the border. I do not want the border on the inside of the image crop, I want it on the outside. I was thinking that the border would be 1/2-inch on each side... effectively making the actual photo 3x5.... adding the borders would give it the 4x6 size I need. So I'm basically looking for the easiest way to add this border to all 288 of my images. I normally get my prints through mpix.com, and they have an option where you can add a white or black border, that keeps the images at the 4x6 size I need, but the border is on the INSIDE of the image, and I cannot have that, due to content I want to keep near the edges of some of my photos, and the vignetting that I use.

Would the best way to do all of this be to open the images in Photoshop (I have CS5) and resize to 3x5 and manually add a 1/2" border to each side?

Create an action:

Open one image.
Start recording the action.
Resize to 3x5 (I'm assuming they already have the correct aspect ratio! Otherwise, resize to 3x4.5)
Enlarge canvas to 4x6, use white as BG color.
Stop recording the action.
Exit without save.

Go to bridge.
Select all images.
Go Tools > Photoshop > Image processor.

Use it to run the action you just created & save the images to a new folder.

You could have added the border in LR as well on export, using LR Mogrify.

Rene, thanks for the tip. The action seems the best way to do it. Yes, they're all set to a 4x6 aspect ratio.

I have tried LR Mogrify to do this, but I seem to recall that it didn't let me add a straight "1/2"" border to each image. I'll have to take another look at it, but I don't think it gave me an "inches" option.. only a percentage. The Mogrify plugin seems to be the best route, as long as it doesn't add it to the inside of the photo.

Just thought I'd update the thread here. I used Rene's tip and went with Mogrify (donated as well, great plugin). Anyhow; here's the final outcome:

Nice!

thank you. I was happy to see it turn out so well.