The problem only happens to me with pictures taken in portrait orientation on my iPhone or iPad. Here is the quickest way I have found to fix it.
In iPhoto, select one or more "black" photos and click Edit. In edit mode, click Rotate 4 times (i.e. 360º rotation). Select the next photo, and Rotate 4 times. Do this for each photo. Then click <Photos to exit edit mode.
All the "edited" photos should now appear.
I have the same issue, except the orginal photos are turning black on my iPhone as well!. I have had to turn off iCloud now to stop it from happening. I tried editing the images in iPhoto on my Mac as suggested by Marc but It does not work. While I am in the editing window the image does appear, but when I got back to photo view it is black again.
I seem to have eliminated the problem, at least for now, by rebuilding the library. So, if you want to try it yourself, this is the process I followed:
- Check for iPhoto updates. If there is an update, download and install the update, then launch iPhoto in case it needs to update your library to the new version.
- Quit iPhoto.
- If you use Time Machine, have it back up your iPhoto library.
- Make a copy of your iPhoto Library file. On my system it is located in /Users/[MyUserName]/Pictures. I just copied it to an external USB drive.
- Rebuild your iPhoto library by following the instructions in http://support.apple.com/kb/HT2638. I only had to use the first rebuild option, "Rebuild the iPhoto Library Database".
Please "like" this if it helps.