IrfanView is designed for fast image browsing. Since it supports almost every file type, it is more powerful than Windows Explorer, and the images can be viewed at full size instead of in a small preview window. Below is the IrfanView toolbar using one of many available skin.
1. From the IrfanView Window
Open any supported file from Windows Explorer, or from IrfanView's File Open dialogue box. To browse all files in the current directory, use the left and right cursor keys, or click on the blue left and right arrows on the toolbar.
When the last or first file in the current folder is reached, you will get a dialogue box asking if you want to continue in another folder. To disable it, go to Properties (P), Browsing/Editing, and check "If the end/begin of folder is reached, loop current folder (during browsing)."
Normally, files will be displayed at 100%. To fit files to the current IrfanView window, go to the View menu and choose one or other of the Display Options. They are self explanatory.
To zoom in/zoom out, use the + and - keys on the numeric keypad, or click the magnifying glass icons on the toolbar. You can also drag a selection rectangle, and click inside it to zoom in. To return to 100% viewing, press Control H.
2. Full-screen Viewing
With any image open in IrfanView, press Enter or double-click to enter full-screen mode.
Use the cursor keys, the space bar, or the mouse to browse all images in the current folder. Press the Enter key again, or the Escape key to return to normal viewing mode.
Fitting of images in full-screen mode can be changed from Properties (P), Fullscreen/Slideshow. File information can be shown in the corner, and the background colour can be selected. There are options to resample images (slow), use alpha blending between images, or stretch images across monitors.
3. Thumbnail Browsing
When you want to browse more than a single directory, it is more convenient to use the Thumbnail browsing mode, which is more like Windows Explorer, but much faster and more flexible.
To enter Thumbnail Mode, press T, or click the multi-coloured thumbnail icon on the toolbar. A new window will open with a folder pane on the left, and a thumbnail pane on the right. If you select any folder in the left pane that contains supported file types, IrfanView will immediately start generating thumbnails to display in the right-hand pane. This process is very fast, but if your images are large it will take some minutes. To pause the process, you can select stop from the menu bar.
To change the size of the thumbnails, and therefore the number of columns that will fit in the thumbnail pane, select the options menu, and “Set thumbnail options.”