pngcrush is an excellent batch-mode compression utility for PNG images. Depending on the application that created the original PNGs, it can improve the file size anywhere from a few percent to 40% or more (completely losslessly). The utility also allows specified PNG chunks (e.g. text comments) to be inserted or deleted, and it can fix incorrect gamma info written by Photoshop 5.0 as well as the erroneous iCCP chunk written by Photoshop 5.5.
gif2png is a simple command-line utility to convert images from GIF to PNG format. It automatically preserves transparency, interlacing and text comments, and it can do multiple images in one command (e.g., gif2png *.gif). The distribution also includes a web2png script that can be used to convert an entire web tree; it calls gif2png to do image conversions, then patches IMG SRC tags correctly in referring pages.
AntTweakBar is a small and easy-to-use C/C++ library that allows programmers to quickly add a light and intuitive GUI into OpenGL or DirectX based graphic programs to interactively tweak them. Program variables can be linked to a graphical control that allows users to modify them. Programmers are not required to design the graphical interface by providing coordinates or by using a visual UI editor. Controls are automatically organized following an optional given hierarchy.
glbmp is a lightweight and portable partial glaux replacement, providing auxDIBImageLoad and related device-independent bitmap image loading functionality. At the basic level, it's a flexible bitmap loader and decoder that can be used anywhere the color data of a bitmap is required. It supports uncompressed monochrome, 16 color, 256 color, and 24-bit bitmap files of any size, and allows for flexible output formats.