Importing Photos into Iphoto

I have scanned some photos using an HP scanner which loaded them to my MacBook Pro in PDF format, which isn't compatible for uploading to iphoto. I changed the format of the files by changing the suffix on each one from .pdf to .jpg and then imported to iphoto. I can see the thumbnails but not when I double click on the pic to view it full size I get a blank box and can't view. Any suggestions? Thanks,

Changing the suffix of a file does not magically convert it into that file. Open the PDF pictures in Preview (which is already on your Mac, probably in the dock), then save them as proper JPGs. Voila, iPhoto will now accept them.

For future reference, you would probably set your scanner to save scans in JPG or TIFF rather than PDF for photos.

How I have the answer it seems so logical - thank you!