US Patent 7440128 Print data compressing method

A print data method includes a slicing step, a compressing step and decompressing step. The slicing step divides a swatch of data to be printed and required by each motor movement into a plurality of slices, each having m bits to represent printed pixels and further divided into n segments, where m, n are integers. The compressing step uses an inter-slice compression to represent an (i+1)-th slice of data on a basis of an i-th slice of data for generating a compressed (i+1)-th slice of data and an (i+1)-th control character. The decompressing step uses an inter-slice decompression with respect to the inter-slice compression to restore the (i+1)-th slice of data from the compressed (i+1)-th slice of data for further printing.