Symptom
Some JPEG and GIF files cannot be imported into iMovie. Some images are available in the Import dialog, some are dimmed. iMovie 2 for Mac OS 9 can import the images.
Solution
If Preview can open the files, you can use Preview to export the images for use with iMovie. Follow these steps:
1. Open the Preview application.
2. Choose open from the File menu.
3. Select and image and click Open.
4. Choose Export from the File menu.
5. Choose JPEG or PICT from the Format pop-up menu.
6. Choose a destination folder.
7. Click Save.
8. Import the images into iMovie.
You can also use a third-party utility to manually add file type/creator codes to the affected file(s).