Step 1: Prepare all the photos that need resizing.
I highly recommend keeping all the photos in one folder. When you’re downloading photos from Dropbox, for instance, choose the images that you’re going to use and download them all at once. You’ll save a lot of time and storage space this way.
Step 2: Open iPhoto and import photos.
In iPhoto, click on “Import” and choose the folder where you kept the photos. Once this is done, all the images in that folder will be imported and displayed.
Step 3: Export photos.
Press “Command + A” to highlight all the photos. Click on “Export.”
Now this is the part where you need to choose the size and the quality of the image.
What you choose would mainly depend on your needs. For example, if I needed to upload screenshots for this in Workplace or Enterprise. Each image needs to be less than 50KB.
After trying different combinations, I found that choosing Medium for JPEG Quality and Size will result in an image that is around 40 to 60KB.
I wouldn’t recommend choosing Low (smallest size). The quality of the image would greatly suffer, and if there are texts, it would be almost unreadable.