feh is a fast, lightweight image viewer that uses imlib2. It is command line-driven and supports multiple images through slideshows, thumbnail browsing or multiple windows, and montages or index prints using TrueType fonts to display file information. Advanced features include fast dynamic zooming, progressive loading, loading via HTTP (with reload support for watching webcams), recursive file opening (slideshow of a directory hierarchy), and mouse wheel and keyboard control.
Gifsicle is a powerful command-line program for manipulating GIF image files. It has good support for transparency and colormap manipulation, simple image transformations (cropping, flipping), and creating, deconstructing, and editing GIF animations. It can also optimize GIF animations for space. Also included is a GIF animation viewer and a program that checks whether two GIFs look the same.
IDS is a CGI written in Perl that generates a multi-gallery photo album Web site on the fly. All you need to provide are the images and (optionally) descriptions. Features include support for internationalization, user interface themes, thumbnail generation for JPEG, PNG, TIFF, and GIF images, and the display of whatever other file types you choose. If you allow them to do so, guests can leave comments and order prints. Your files are searchable by name and description, and can be managed via a Web-based administrative interface.
Java PictDraw is a set of Java classes to display Quickdraw images (Macintosh Pict files). Quickdraw is a meta/vector format that supports lines, circles, arcs, boxes, polygon, styled text, bitmap-based regions, and compressed bitmaps (RLE and JPEG). This package contains all the classes needed to parse a Quickdraw file, and to display into a Java AWT port. Features include the ability to make the text regions of the picture clickable.
These are the demo programs that accompany O'Reilly's "PNG: The Definitive Guide." rpng is a simple file viewer with the ability to set a background color when displaying transparent PNGs. rpng2 is a progressive PNG viewer, designed to work like a web browser (though it contains no network code); it can generate a background image when displaying transparent PNGs. wpng is a simple converter from NetPBM to PNG format; in most respects it is much more limited than pnmtopng, but it supports interactive entry of PNG text annotations and will generate noninterlaced PNGs on the fly (rather than buffering the entire image first like pnmtopng). The viewers include simple front ends for both X and Win32; the converter is a command-line app that compiles on Unix, Windows, and probably other platforms.
TkDVI is a DVI previewer built with the Tcl/Tk toolkit. It can use multiple windows to display multiple pages at the same time (which can come from multiple DVI files sharing a common font repository). Each window can show either a single page, two facing pages (as in a book) or sixteen reduced pages in the space of one, to check page breaks and positioning of floating items. TkDVI supports many features from xdvi, such as a magnification glass, but also adds interesting stuff like a gv-like page selector and a `rubber line' for measuring distances. TkDVI is based on a reusable Tk `image type' for DVI files which can easily be incorporated in other programs, and it is straightforward to customize and extend TkDVI itself.
IIViewer is an application for X, and optionally for the Linux framebuffer device. It allows you to display pictures in a directory as thumbnail images. Selected images can then be displayed at full size. It reads BMP, GIF, and JPEG images (even without additional libraries), but it is also able to use libjpeg, libtiff, and libpng.
The Webcam Network is a network of webcam/image publishers and subscribers. Users can publish to the network using the publisher tool and subscribe to the network using the viewer tool. The publisher tool will push images to the network at an arbitrary rate, and the viewer will display image updates from selected publishers in real-time with resizing, scaling, or in collage mode. The viewer can also render to the root window.