Mac batch image resizing and conversion FAQs: How can I batch resize images or batch convert images on Mac OS X?
I was really pleased lately to discover I already had some free Mac batch image processing software already installed on my Mac computers. It turns out that the Mac Automator program from Apple was created with several "workflows" in mind, including several batch image processing workflows. With the Automator you can batch resize images, batch convert images file types, and batch create image thumbnails.
As I learned about these image processing capabilities, I wrote a number of tutorials, and I'm linking to those tutorials below.
1) Batch image resizing
If you need to batch resize a group of photos/images, take a look at my How to batch resize images (batch image resizing) tutorial. That tutorial provides a step-by-step guide on how to use the Mac Automator to scale a collection of photos/images.
If you're not afraid of the Mac command line, you can also pop open the Mac Terminal application, install an application named ImageMagick, and learn How to batch resize images with ImageMagick, though admittedly this is for users not afraid of the command line.
2) Batch image file converter (image file format conversion)
If you need to convert a group of photos from one image format to another, take a look at my Batch image file converter (JPG, PNG, BMP, PDF) tutorial. Again, it shows how to use the Mac Automator to convert image files from one image file format to another, including BMP to JPG, PNG to JPG, PDF to JPG, and every other conceivable direction.
3) Batch image thumbnail creation (thumbnail photos)
If you need to create thumbnail images from a batch of photos/images, take a look at my Batch thumbnail image creation tutorial, which again walks through a simple Mac Automator workflow to create thumbnail images from your original batch of photos.
4) Simple Mac image resizing with Automator
In a related note, if you want to create a simple Mac app to resize images, I just wrote this article on how to quickly resize images on Mac OS X with a free Mac app. That article describes how to create your own, free Mac app using the Mac Automator application to resize your photos and images using drag and drop techniques. (It's very easy to create Mac apps using the Mac Automator; if you haven't done it yet, give it a try. You'll thank me later. :)