NConvert Review
NConvert is a powerful command-line multi-platform batch image processor with over 80 commands. It can process thousands of images at once, and is compatible with over 500 image formats. Its extensive set of editing tools includes options for adding text captions and watermarks, cropping images, adjusting levels, contrast and brightness and applying filters to create different effects. It also provides the option to create animated GIFs and TIFFs, and to perform lossless compression of files. Although it is a command line application, its English-like syntax means that it is fairly easy to use for those accustomed to working from the console.
It works on Windows, Linux and Mac OS X and is available as freeware. It supports a huge number of image file formats, and it's particularly good at converting very large files. It's fast too - I've found that it beats the conversion speed of some paid software programs. It doesn't require you to upload your files online and has a handy preview function that shows how each photo will look when it's finished. However, if you want to do multiple conversions at once or you're comfortable messing around with advanced settings, you might find it better to try an actual software program.
This software is very comprehensive and includes a number of useful tools for more experienced users. It can automate workflow by watching folders for new or updated images and then automatically apply a custom set of edits to them, including conversion, renaming and compression. It also has many other features for adjusting and manipulating images, such as adding alpha channels, filter effects, resizing or changing the shape of images, and performing complex cropping operations. The software can also create animated GIFs and TIFFs, perform lossless compression of files, and turn photographs into drawings or paintings. Its interface is simple and intuitive, and the app's user manual is well written.