An image processing apparatus sequentially reduces a document, while
changing the reduction factor step-by-step. Next, the image processing
apparatus refers to the characters that constitute the document that has
been reduced with the respective reduction factors, and specifies a
reduction factor at which blank regions surrounded by line portions that
express each character do not disappear. When an appropriate reduction
factor is specified, the image processing apparatus specifies a
resolution of the characters for that reduction factor, and converts the
resolution of the document data to that specified resolution. Then, the
image processing apparatus performs various processing for the document
data whose resolution has been converted. Thus the resolution of document
data is converted such that the document is reduced with a reduction
factor suitable for computer processing.