To compress the images without losing quality there are several image compression software.
But to have high compression rate and image Quality both I recently found a new image compressor: RIOT
I tried this. It compressed an image of 570 KB into 45 kb
1. Select JPEG, PNG, GIF image formats.
2. Resize multiple pics at a time.
3. It is FREE.
4. Image Adjustments.
5. High compression rate.
Download link: http://luci.criosweb.ro/riot/download/