Gwenview
A simple image viewer for KDE featuring a folder tree window and a file list window and has a thumbnail view.
KFourier
An image processing program that uses the Fourier transformation to use multiple filters on an image.
KIllustrator
Free vector-based drawing application for KDE, similar to Corel Draw or Adobe Illustrator.
KolourPaint
KolourPaint is a free, easy-to-use paint program for KDE.
Krayon, KPaint and KIconEdit
Also known as KImageshop, Krayon is a painting application for professional artists and serious amateurs. KPaint is an application for creating, and working on images in any of the standard formats like jpg or png. KIconedit is a popular editor for small graphics like icons, logos, banners and webpage buttons.
mvComicsMaker
A graphics editor for creating bitmap and vector animations.
Pixie Plus
(formerly ImageForge) An image browser, viewer, and image/photo editor for KDE2.
QtVu
(pronounced CuteView) An image viewer for The X Window system. It is inspired by ACD System's excellent ACDSee.