Tips

Using the mouse

Panning with the mouse
Holding down the left mouse button on an image allows you to scroll the image.
The mouse wheel will scroll the image up and down.

Zooming with the mouse
Clicking the middle mouse button will toggle the auto zoom on/off.
Hold down the key, then either use the mouse wheel to zoom in and out or left click to zoom in and right click to zoom out.
The mouse wheel, used while holding down the key, will scroll the image horizontally.

Browsing with the mouse
When in Browse mode, clicking an image switches into View mode and shows that image.
When in Browse mode, scrolling the mouse wheel will scroll up or down the thumbnail view area.
If the Mouse wheel behavior option in Settings Configure is set to Browse, scrolling the mouse wheel while in View Mode will move you through the images in the folder.

Key bindings
comes with a range of keyboard shortcuts, all of which can be viewed and remapped by selecting Settings Configure Shortcuts.... Note that in the Files and Folders windows, all the normal KDE shortcuts are functional, unless otherwise remapped.
A few of the most useful default bindings are:
Space: Displays the next image in the directory.
: Displays the previous image in the directory.
Up: Moves to the parent folder of the current folder.
F: Switches into Full Screen Mode.
: Switches back to Browse Mode.
M: Show or hide the menubar.
B: Show or hide the Thumbnail bar.
F4: Show or hide the Sidebar.
F6: Make the Location bar editable so that you can directly type in a file path. You can return to the standard Location Bar by pressing the arrow at the right.
R: Rotate the current image to the right.
L: Rotate the current image to the left.
R: Resize the current image.
C: Crop the current image.
Y: When multiple images are displayed in View Mode, this synchronizes their views.
S: Save any changes made to the image.
Del: Move the current image to the trash.
Del: Permanently delete the image from the disk. Note that this operation is irreversible and cannot be undone.
P: Print the current image.
O: Open an image using the standard file selection dialog.
F: Pressing this shortcut toggles zoom-to-fit on and off.
P: Viewing a video this shortcut toggles playback on and off.
T: Edit tags.
F2: Rename an image inline.
Del: Move an image to the trash.
Del: Delete an image.
F7: Copy an image.
F8: Move an image.
F9: Link an image.

Advanced Configuration Options
Some notes on hidden options can be found on this page.
The options described on the above-mentioned page may help you tune for specific needs, but please keep in mind there is no warranty they will continue working from one version to another.