RIOT stands for Radical Image Optimization Tool. It is a free software to convert format of your images, and reduce their size while still achieving good quality. It can work on normal image formats (bmp, png, gif, jpeg etc.), and also psd files.
Some of the good features of this free Image Optimization Tool are:
- Shows original and optimized image together.
- You can see the optimized quality and filesize before finalizing the format. Then you can tweak the settings to get to your desired file size.
- Can alternately display original image over optimized image so that you can compare quality of both.
- Can strip image metadata to reduce file size further.
- Very fast processing, as everything is done in memory.
- Supports some common image functions, such as pan and zoom.
- Produce web-ready images that are small in size, and still of good quality.
RIOT is available both as a stand alone application, and as a plugin for Irfan View so that you can compress images directly in IrfanView.
I like RIOT for its simplicity of ease, nice quality of output images, and the fact that it is absolutely free. Download using links at the end.