Anyone who has posted images to a Web site or blog knows that making the image "Internet-friendly" is crucial to fast page-loading times. Similarly, optimizing images for e-mail is important because sending enormous image files through your e-mail client can cause problems for those with slower connection speeds. There are several software tools available to reformat and optimize your images, but I found one recently that's free, easy, and effective.
RIOT (Radical Image Optimization Tool) (Free) for Windows takes the side-by-side interface approach for painless image optimization. Those who have used Adobe ImageReady will immediately recognize the layout of the interface, with the original image on the left and the optimized image on the right. The file size is listed above both the before and after images, so you can tell how your tweaks will affect the end result. You also can zoom in to see how much your changes effect image details.
If you've ever optimized images before, you know that there are many ways to lower image size without degrading the quality of the image to the human eye. RIOT lets you output to Internet-friendly formats like JPEG, GIF, or PNG, and lets you tweak different settings for each format. For a JPEG image, you are given a slider you can adjust to tweak the quality or you can adjust between four levels of Chroma subsampling (Wikipedia link) to reduce size. GIF and PNG formats allow for color reduction (often the most effective method), which you can choose from a dropdown menu or use a slider. Alternatively, RIOT also lets you choose between two predetermined color quantization algorithms to take the guesswork out of optimizing. Our favorite feature is the "Compress to size" button, which lets you pick your optimal size and RIOT gives you the result. Obviously, you'll need to experiment with this option to get your desired results.
Along with the handy side-by-side optimization features, RIOT offers basic image editing tools like rotation and flip horizontal and vertical. We should point out that RIOT is still in beta, but in all of our tests the software performed without a hitch. One thing we would like to see in future versions is the capability to batch optimize, but as a standalone, free image optimization tool, RIOT is definitely worth checking out.