A lot of us will unanimously vouch that iPhoto 11 is the best way for Mac users to manage, edit, and share photos, but some Mac users may not take enough photos to warrant purchasing or bothering with the program. In addition, you may simply need to quickly resize images without bothering to open iPhoto, which sometimes can mean opening a huge library of thousands of images.

For more streamlined purposes, Apple’s default OS X applications, Preview and Mail, and a free lite version of a third party application called ResizeIt may suffice. If you, on the other hand, need to do batch resizing of images, check out my article on using Automator for this purpose.

Resizing In Preview

By default, when you double-click on an image on your Mac, Preview is the application that opens it up. What you may not know is that it’s also a good application for resizing images. To do so, open an image into Preview, and click Tools > Adjust Size in the menu bar.

The drop-down window will provide you information about the dimension and resolution size of the image. For images you’re going to post for viewing on a website, the resolution size 72-150 pixels is adequate. For printing purposes, 240 to 300 pixels should be used. You should manually type in the dimension for resizing your image.

Or you can use one of the presets provided in Preview. It used to be that 640 x 480 pixels was the standard size for posting images on the web, but with many people viewing the web on widescreen monitors and small mobile phones, you might need to consider other sizes, such as 800 x 600 or the smaller 320 x 240. Unfortunately, Preview doesn’t allow you to save custom sizes as a preset. If you have a custom size you need to regularly use, create an Automator workflow or use ResizeIt described below.

Caution: when you resize images in Preview it will not give you the option to save the original of your image. So you need to either make a duplicate copy of the photo before resizing, or select Save As to make sure you’re saving the resized image as a separate file.

Resizing In Mail

If you want a super fast way to resize an image(s), simply drop it into your Apple Mail application and mail it. Done. Mail even provides you with options for resizing.

At the bottom of the composition box, Mail will tell you the dimensions of the resized photo before you mail it. You can change it to Small, Large, or Actual Size, provided the recipient of your email has a fast enough Internet speed to download a large size image file.

The great thing about using Mail to resize an image is that it doesn’t resize your original. It makes a copy and then resizes it. However, if you try to drag the image out of your drafted email, it will not be the resized version.

Resizing In ResizeIt

If you don’t want to haul out iPhoto or Photoshop to resize an image, and if you need to do some quick batch resizing of images, a small free application, ResizeIt available in the Apple Mac Store, may do the trick. Now I must say, ResizeIt could use some work, although it does what it says it will do.

The best way to use ResizeIt is to select, then drag and drop one or more photos onto the ResizeIt icon in your Dock. From there you will be presented with a dialog box in which you configure the settings you need. Be sure to leave the Overwrite Files box unchecked if you don’t want to resize your original image(s). If you leave the “Choose the folder to save images” unchecked, ResizeIt will resize, save, and put your images into a folder for you.

You can also save various sizes as presets. The application worked OK for me. I do think however that the pixel boxes should start with “W” and then “H”, for that’s typically how dimensions are set in image applications. The first number is usually the width and the second is height. But ResizeIt is a free application, so not much to complain about. It’s a useful program for quick batch resizing.

Finally, if you click on Script > Generate Droplet, ResizeIt will produce an AppleScript script that you can save as a droplet application. It‘s sort of like creating an Automator application for resizing images. So for example, if you regularly need to resize photos to a particular size, like 800 x 600, then you simply create the preset in ResizeIt, and then have the application create a droplet for that size. The code will open up in AppleScript and you can save it as an application that you can keep in your Dock. From there, you just drop your images onto the droplet and, viola, they get automatically resized. That‘s the way computers should work.

The key to resizing images is to have as many options to do so. No one wants to receive or view an oversized image. Let us know if you have any other strategies for resizing images. For Windows users, check out Simon‘s article on resizing photos.

In an article that’s soon to follow, we will give iPhoto it’s due when it comes to resizing photos. Stay tuned.