Is there a way to merge two photos into one using iphoto?

Short answer is no. However, if you do not mind Preview, which is part of OS X, you can do it for free. Here is a link to a useful and clever tutorial.

This solution uses only Preview and may be handy if you can't install software on a machine. It is, however, not elegant.

Say your images are called A and B. Then:

1. Open A in Preview.
2. Select All, Copy.
3. In the Tools menu, select Size and adjust the width to the sum of the width of the two images (in your example, 640 px). Keep the height. This will result in a stretched version of A.
4. Paste the copy of the original A and move it manually to the left.
5. In another window, open B.
6. Select All, Copy.
7. Paste into A, moving it to the right.
8. Save as a new image.

Since, of course, Preview does not offer any proper image editing tools and no way to exactly position the two images, the ImageMagick solutions posted here are preferable. (Or why not just install MacPorts' GIMP package while you're at it and enjoy a fully equipped image editor?)

No. You'll need a photo editor for that.

In order of price here are some suggestions:

Seashore (free)

The Gimp (free)

Graphic Coverter ($45 approx)

Acorn ($50 approx)

Pixelmator ($50 approx)

Photoshop Elements ($75 approx)

There are many, many other options. Search on MacUpdate. You can set Photoshop (or any image editor) as an external editor in iPhoto. (Preferences -> General -> Edit Photo: Choose from the Drop Down Menu.) This way, when you double click a pic to edit in iPhoto it will open automatically in Photoshop or your Image Editor, and when you save it it's sent back to iPhoto automatically. This is the only way that edits made in another application will be displayed in iPhoto.

Thanks for your solution! It worked like a charm. I had a single page in PDFFiller and was able to do a couple of screen captures (expanded into full-screen mode so I only needed two) and merged them per your instructions. Paid attention to the pixel width while capturing, turned off the proportional check box before resizing, and ended up with a perfect document.

Thanks for your solution! It worked like a charm. I had a single page in PDFFiller and was able to do a couple of screen captures (expanded into full-screen mode so I only needed two) and merged them per your instructions. Paid attention to the pixel width while capturing, turned off the proportional check box before resizing, and ended up with a perfect document.