Select TWAIN Source
Click on the File Menu, then Select TWAIN Source.
Allows you to choose from the scanners or any other TWAIN compatible device (digital camera, TV card, etc.) installed on your computer (if more than one is available).
Note: this dialog is showed/managed by Windows, not by IrfanView.
Click the name of the device you want to use, then the Select button. To exit without making a selection, click Cancel.