You can use commercial tools like Photoshop, Pixelmator, or familiarize yourself with free utilities like Gimp to resize large photos. There are already a bunch of apps available to help you resize the locally stored photos on your Mac.
For instance, you can also use image editing tools like Skitch to capture screenshot and change the size of the captured images. Snagit (paid app) is another alternative to resize and animate your photos.
But what about resizing hundreds of photos? How do you batch resize photos on your Mac? In such cases, you can either use Apple’s photo management app or try out Shrink O’Matic.
Batch Resize Photos on Mac
If you want to easily and quickly resize JPG, PNG, GIF images, then Shrink O’Matic is your best bet. This nifty little app is available for Windows and Mac OSX.
This utility is as simple as it gets. Set the width and height of the photos, then select the naming method for your images — auto-rename or same as original — and finally select the quality of the output photos. Then all you have to do is to drop the pics in the Shrink O’Matic window and the converted images will be automatically saved in the same folder.
Shrink O’Matic is an Adobe Air application. If you have installed Adobe Air on your Mac, visit this page to get Shrink O’Matic.
Alternately, you can also use iPhoto, which is Apple’s photo management app, that not only recognize faces but also resizes photos instantly. Select a group of photos you’d like to resize, go to File -> Export. The Export Photos window appears.
There’s an option to scale the images to no longer than the specified width and height. You can arrange custom size for all your photos and export them in bulk in one-click.