Method and apparatus for controlling a compression rate for a file

An apparatus for determining a target compression rate for a file, the apparatus comprising:

• a storage unit for storing a first correlation between an initial compression rate and a size of a first file compressed at the initial compression rate, and a second correlation between the initial compression rate and a size of a second file compressed at the initial compression rate;
• an input unit for inputting a third file;
• a compression unit for compressing the third file using the initial compression rate;
• a first calculation unit for calculating the difference x between the size of the compressed first file and a size of the compressed third file and the difference y between the size of the compressed second file and the size of the compressed third file;
• and
• a second calculation unit for calculating a target compression rate using a target file size for the third file and the differences x and y.

A method for compressing a file comprising using a processor to perform at least the steps of:

• compressing a target file at an initial compression rate and determining a size of the compressed target file;
• comparing the size of the target file compressed at the initial compression rate to sizes of a first file and a second file compressed at the initial compression rate;
• based on the comparisons and a target size for the target file, calculating a target compression rate;
• and
• compressing the target file using the target compression rate.