The free and portable Radical Image Optimization Tool (RIOT) has been an app I’ve recommended for a few years now (I think I’ve been using it since about 2008). As the name suggests it focuses on doing one thing, and doing it well: optimizing images. It can compress, resize, adjust, and convert your images in a way that leaves you in control of the end result.
The thing I like the most about riot is how easily I can manipulate multiple photos in just a few clicks. Thanks to the “batch” button on the toolbar I can select an entire folder of images that I want to resize and/or compress, and the speed at which it can process the images is rather incredible. This is great for emailing off a slew of photos when you’re concerned about the attachment size.
Most of the time I use RIOT for batch optimizations, but this regularly-updated app is equipped with all kinds of other features:
- Open many image types including rare/scientific types
- Save and optimize JPEG, GIF and PNG with a simple, clean user interface
- Works in dual view: (original – optimized image) or single view (optimized image).
- Automatic preview of resulting image
- In-place compare function (alternativelly display the original image over the optimized image to notice small pixel changes)
- Compress files to desired filesize threshold
- Fast processing (all is done in memory);
- See instant results including resulting filesize
- Batch support (process multiple files at once)
- Transparency handling options
- Decide if you want to keep metadata (comments, IPTC, Adobe XMP, EXIF profiles, ICC profiles).
- Transfer metadata between image formats (destination format must support them)
- Common tools: pan and zoom, rotate, flip
- Basic image adjustments: brightness, contrast, gamma, invert
- Visually reduce number of unique colors for PNG and GIF images in order to reduce filesize
- Resize image by using well known resample filters (ex: Lanczos3, Catmull Rom, Bicubic, and others)
- Compression and the results are comparable to those of commercial products, even higher.
- Adaptive logarithmic tone mapping algorithm (Drago) used for HDR images
Seeing that RIOT is free and portable you can give it a try without much worry. I highly recommend keeping this one in your toolbox.
RIOT Homepage (Windows only; Freeware/Portable)