Is there a setting to enable Irfanview to open a large imaze to fit your desktop? It's annoying browsing through an SD card and having to manually resize them so you can see what the photo looks like.
View > Display Options (window mode) and select
Fit images to Window or
Fit Only big images to window.
If you maximize the IrfanView window, the first option (
Fit images to Window) should suffice. This will scale up smaller images, and scale down the larger ones.
If you keep IrfanView windowed, then the second option will only rescale images that are larger than the IrfanView window. Images that are smaller will display at their native resolution.
What Scott said, and:
Shift-W will select fit image to Window in no-fullscreen mode.
Ctrl-H will display image at full size (pixel per pixel) in non-fullscreen mode.
The above are extremely useful when editing - allowing either overall view or detailed close-up.