Scan Again is a GUI front-end for SANE (Scanner Access Now Easy).
It searches for scanners, putting the results into a pop-up at the top of the window.
The “Preview” button causes a low-resolution scan to be made and displayed in the window. It is possible to limit the detailed scan to a selected area of the image, to save time and file size, by drag-clicking a selection rectangle across the preview image.
The “Scan” button causes a detailed scan to be made, after you have a chance to choose the file name and location for the result. The only file type that is supported currently is TIFF. This scanned result will be opened in another application if you have that checkbox checked. The default application is Preview, but you can choose others with the “Choose” button.
You can also use the program as a “copier”, by pressing the “Copy” button. This will scan the image, and send the result to a printer.