A color conversion section converts R-, G- and B-image signals input by the reading
of a color image on an original to C-, M- and Y-color signals. A histogram producing
means of an image processing section produces density histograms of the respective
color signals on the basis of the converted C-, M- and Y-color signals. An original
type determination means determines a type of the original on the basis of the
histogram data signals. A colored background determination means determines a colored
background on the basis of the histogram data signals. A background process presence/absence
determination means determines whether a background process is to be executed or
not, on the basis of an original type determination result signal and a colored
background determination result signal. A CPU produces, when it is determined that
the background process is to be executed, a background process table using the
density histogram values of the respective color signals. A density adjustment
means performs density adjustment of the respective color signals input from the
color conversion section, on the basis of the background process table.
