Ximagic Quantizer - Ximagic Quantizer Toolbox with 10 color reduction filters (uniform, popularity, octree, median, wu, dennis lee, binary split, neuquant and scolorq) and 11 dithering filters error diffusion:(floyd-steinberg, fan, jarvis, stucki, sierra3, sierra2, sie…
ImBatch - ImBatch is a batch image processor with a nice graphical user interface.
jStrip - jStrip is a free tool to reduce the file size of JPEG images without sacrificing image quality.
Batch Image Resizer - Resize, crop, shrink, flip, exif-rotate, convert, enhance, process multiple pictures and photos with professional software! 120+ Actions, 30+ Image Formats
Caesium Image Compressor - Compress your pictures up to 90% without visible quality loss.
DVDVideoSoft Image Convert and Resize - Free Image Convert and Resize is a compact yet powerful program for batch mode image processing.