Digital camera today have become so powerful that they generate very detailed images of sizes as large as 5 MB for a 12 Mega Pixel camera.The problem comes when sending these pics or sharing them.If you don't have then its a big headache uploading them over internet.
JPEG 2000 format allows for high compression with high quality.
For compressing you need to download and install XnView .
Download Xnview version 1.98.5 (4.3 MB)
Download Xnview latest version
Download Xnview portable (4.1 MB)
Run xnview follow the instruction as given in the video below
In this video a 246 KB jpeg image is compressed to 33 KB file at almost same quality.
If viewing problem then Download video file (300 KB)