Graphical tools that come with Linux system.

GNU Image Manipulation Program (GIMP)

• GIMP is the GNU Image Manipulation Program. It is a freely distributed piece of software for such tasks as photo retouching, image composition and image authoring. It works on many operating systems, in many languages.

 

F-Spot Photo Manager   

• F-Spot is a full-featured personal photo management application for the GNOME desktop.
• F-Spot simplifies digital photography by providing intuitive tools to help you share, touch-up, find and organize your images.   

OpenOffice.org Draw

• OpenOffice.org Draw is a vector graphics editor and is part of the OpenOffice.org office suite. It features "connectors" between shapes, which are available in a range of line styles and facilitate building drawings such as flowchart. It also includes many features found in desktop publishing software.
• OpenOffice.org users can also install the Open Clip Art Library, which adds an extensive gallery of flags, logos, icons and banners for general presentation and drawing projects. In particular, Linux distributions Debian and Ubuntu have provided ready-to-use openclipart packages for easy download and install from their online software repositories.  

gThumb Image Viewer

• gThumb is an open-source image viewer and organizer for the GNOME desktop environment released under the GNU General Public License. It was originally based on GQView, and is designed to have a clean, simple interface.
• gThumb allows the filesystem to be browsed for images. They can be organized into catalogs, or viewed as a slideshow. Folders and catalogs can be bookmarked, and comments may be added to images.
• Via gPhoto it can also acquire data directly from digital cameras.
• Many basic image editing features are included, such as: rotation, resizing, cropping, and image enhancing filters such as color, brightness and contrast adjustment.