Mac's built-in Automator can reduce image sizes.
- Open Automator (inside
- Choose Application as the document type.
- Click "Photos" in the Left Column.
- Drag "Scale images" into the Actions Area.
- Click Add.
- Choose Scale image "By Percentage."
- Choose 50%.
- Click Run.
- Click OK.
- Click Save in the Automator File Menu.
- Name it image
resize 50%.app. It saves to Applications Folder.
- Double-Click the icon in Applications.
- Right-Click the app in the dock and select Keep in Dock.
- Now, any image you drag onto this Dock icon will Duplicate and Reduce image Size by 50% (so 12 MegaPixels will become 6 MegaPixels).
Consider storing your photos on an external hard drive or USB flash drive of proper capacity. You can also ignore iPhoto, and store all your images in the "Photos" folder. Use Image Capture to import new images from your Camera or Camera's Memory Card.
Also, when taking photos in your 12 megapixel camera, go in the Settings menu on there and change the capture size to a lower megapixel Size. If you have a large memory card, you can take the same photo in several different sizes.