PUBLIC MARKS from srcmax with tags png & optimisation

Trimage is a cross-platform GUI and command-line interface to optimize image files for websites, using optipng, pngcrush, advpng and jpegoptim, depending on the filetype (currently, PNG and JPG files are supported). It was inspired by imageoptim. All image files are losslessy compressed on the highest available compression levels, and EXIF and other metadata is removed. Trimage gives you various input functions to fit your own workflow: A regular file dialog, dragging and dropping and various command line options.

Advanced lossy compression for PNG images that preserves full alpha transparency.

OptiPNG is a PNG optimizer that recompresses image files to a smaller size, without losing any information. This program also converts external formats (BMP, GIF, PNM and TIFF) to optimized PNG, and performs PNG integrity checks and corrections. If you wish to learn how PNG optimization is done, or to know about other similar tools, read the PNG-Tech article A guide to PNG optimization.