This portable .exe viewer comes in a super clean interface that lends itself to performing the job at hand without distraction. It supports drag n' dropping and supports around 200 different file formats. You will be able to quickly open an image and browse through a collection without any hassle via your arrow keys. Tom's Editor Desktop also includes a bottom status bar which can be used for displaying image details like resolution, format, and name.
Tom's Editor Desktop is designed to provide simple image conversions, but you are limited on the available output formats as it only allows BMP, GIF, JPEG, PNG, and PNM. That said if you are looking for a simple-to-use tool for fast image conversions without a lot of overly complicated configurations, then Tom's Editor Desktop will do the trick.