Almost all image editing programs, including the good-old MS Paint, have built-in resizing tools to help you quickly change the dimensions (or resolution) of your photos. However, if there were a requirement to resize a large number of images to multiple sizes, you might have to take the help of more complicated tools like GIMP or even Photoshop.
There’s a new Dropbox-based option as well that can help you resize a large number of images automatically without requiring any additional software - it’s called SizzlePig.
SizzlePig connects to your Dropbox account and then continuously monitors a particular folder inside your main Dropbox folder. As soon as you add any new images to this “watch” folder, SizzlePig resizes the entire batch in the required dimensions and copies the processed images back to your Dropbox folder.
To get started, you need to define the input and output folders (they should exist inside your Dropbox folder) and also specify the various sizes that your images should be resized to. Advanced users may also experiment with different image formats should they wish to reduce the size (and the visual quality) of the processed images.
Also, if you aren’t too happy with the quality of compressed images, you can always manually adjust the scale or the crop dimensions of individual images and SizzlePig will remember your preferences for images that have the same name.
The service is in private beta though it is expected to go live later today. Also, it is completely free at this time though it is unlikely to stay like that forever.
Also see: Crop your Images Intelligently