Abstract: As for read-out image data of a manuscript, image regions not requiring color output are specified as specified regions 1 and 2. Then, it is determined whether the color information of the pixels of the read-out image data outside the specified regions 1 and 2 is achromatic. When it is determined as achromatic, the read-out manuscript is determined as a monochrome manuscript, so that processed image data in which chromatic pixels of the read-out image data in the specified regions 1 and 2 are converted into achromatic pixels is outputted as achromatic (monochrome) data. On the other hand, when it is determined as not achromatic, the read-out manuscript is determined as a color manuscript, so that the read-out image data is outputted intact as chromatic (color) data.

Abstract: A high-voltage power pack includes: a switching circuit for effecting switching control of a low-voltage d.c. signal to generate a low-voltage a.c. signal; a high-voltage transformer for increasing the voltage of the low-voltage a.c. signal outputted from the switching circuit to generate a high-voltage a.c. signal; a combination of a rectifying circuit and a low-pass filter for rectifying and smoothing the high-voltage a.c. signal to generate a high-voltage d.c. signal; resistors dividing the high-voltage d.c. signal obtained from and smoothed through the rectifying circuit and low-pass filter; a feedback circuit for controlling the switching circuit so that the potential at a divided point between the resistors may be kept constant; and an a.c. power source for applying an alternating current to the divided point, the alternating current having a frequency component transmissible through the low-pass filter, whereby an a.c. superimposed voltage made of the high-voltage d.c. signal with an a.c.