Abstract: Disclosed is a method for correcting a facial region detected from image data for photoprinting of improved image quality. The method includes an image data input step of inputting the image data to an image processing device; facial region detection step of extracting a skin color region from the inputted image data and detecting a planar face or a rotated planar face from a face-existing candidate region; a region division step of dividing the facial region detected in the facial region detection step; a correction step of extracting a distortion data value from the region divided in the region division step and conducting correction; and a photoprinting step of visually outputting the image data finally corrected in the correction step. Various types of distortion of the facial image is effectively corrected before it is printed by a photoprinter so that the image quality is improved.

Abstract: A threshold modulation method, includes the steps of: a) determining whether an input pixel value is greater than a threshold of a current input pixel from the original digital image; b) determining whether an output image value is a predetermined high level or low level based on the threshold; c) if the input pixel value is greater than the threshold and the output image value is the predetermined high level, modulating the threshold of the adjacent pixel; d) if the input pixel value is greater than the threshold and the output image value is the predetermined low level, modulating the threshold of the adjacent pixel; e) if the input pixel value is not greater than the threshold and the output image value is the predetermined low level, modulating the threshold of the adjacent pixel; and f) if the input pixel value is not greater than the threshold and the output image value is the predetermined high level, modulating the threshold of the adjacent pixel.

Abstract: A sheet post-processing apparatus comprises a conveyer for conveying the sheets discharged from the image forming system; a conveying device for conveying the sheets discharged from the image forming system; a pair of upper trays for accommodating the sheets conveyed by the conveying devices, and being horizontally moved in order to align the sheets accommodated therein and fall down the aligned sheets; a pair of upper tray driving devices for providing a driving force to the upper trays; a transmission unit for transmitting the driving force of the upper tray driving device to the upper trays; a lower tray for loading the sheets fallen from the upper trays; and a lower tray driving device for moving the lower tray in upper and lower directions in order to retain distance between the upper trays and the lower tray within a predetermined range. Thus, the sheet post-processing apparatus can accommodate variant size sheets by mechanism consisting of simple and cheap elements.

Abstract: The present invention provides an apparatus capable of selectively stapling one of opposite corners of the sheets, as well as a side of the sheets.