Easy to Use Batch Image Editor with Watermark features....
If you want a lightweight image editor that you can use to perform basic editing tasks such as cropping, renaming, resizing and even applying watermarks to your pictures, then consider rEASYze. You can work with single or multiple images simultaneously.
This is a lightweight and fast library for reading and writing any PNM file - PBM, PGM and PPM, up to 16 bits per sample, in ascii/binary format. Library contains also a Python bindings - module pixfiles with PixFile class.
Very simple and lightweight multi-threaded C# application that I threw together in order to convert a folder full of images from one file format to another. I find this very useful for uploading images from my digital camera to the web.