ABSTRACT
During the last decade, there was an explosive growth of images and photos on the Web. Facebook announced in October 2012 that they have hosted 220 billion photos, and further, the amount was increasing at several hundred million every day [1]. Chinese Tencent announced in August 2012 that they have hosted over 150 billion photos [275]. Microsoft also announced in October 2012 that its cloud storage SkyDrive has hosted 11 billion photos [276]. Let us assume the size of every photo is 2.5 MB on the average, 200 billion photos needs 500,000 1T hard disks to store. For data safety, multiple copies (e.g., three copies) of every photo are needed and hard disks have to be replaced every three years. The current price of 1T hard disk is about $60 and thus the storage cost will be about $90 million per three years even without considering the cost of power supply and air conditioning. As a result, there is an urgent need for more efficient compression for cloud photo storage.
