Image Resize from Jason Pan is a useful iOS utility that allows you to quickly and easily resize an image captured with your iPhone's camera. I use the app to prepare images for blog posts on my family blog. Instead of relying on Wordpress to resize the images to correct dimensions, I prefer to do it myself using this tool.
Resize Image has all the major features required in an image resizing tool. You can import an image from your photo library or capture one directly using the camera interface within the app. The camera is barebones with options limited to flash on/off/auto and front/rear camera.
Once you have an image, you can resize it down to standard sizes measured in megapixels or percentages. You can choose which standard you want to use by default and change the default sizes to suit your needs. You also can adjust the width and the height of a photo manually with the option to maintain the aspect ratio if you want to scale the image down. There is an undo button if you need to roll back your changes.
When you are done resizing, you can export the image to your camera roll, share the image on a social network, send it via email or messaging or pass it on to another app.
Resize Image is available in the iOS App Store for free. It is compatible with the iPhone and requires iOS 6. The app includes ads, but they are subtle and do not interfere with the usage of the app. The ads can be removed via in-app purchase of US$1.99.