Patent ID: 7444024

Claim:
An image compression method executed by a computer, comprising: a main scanning step of scanning bit map data which indicates an image by an array of pixels of main scanning and subscanning directions in the main scanning direction; a first area separation step of separating the data into an area including a black pixel and an area including no black pixel by units of a predetermined number of logical lines based on a result of the main scanning; a subscanning step of scanning the area including the black pixel which has been separated in the first area separation step in the subscanning direction; a second area separation step of separating the data into a coded area coincident with a predetermined coded pattern and a noncoded area noncoincident with the coded pattern; a third area separation step of separating an isolated column coincident with a predetermined isolated pattern from the noncoded area separated in the second area separation step; and a coding step of coding the areas by combining a code indicating the isolated column with a code indicating the number of columns of an area adjacent to the isolated column when the areas separated in the first to third area separation steps are coded as elements.