DIGITAL PICTURE QUALITY IMPROVING METHOD AND APPARATUS

摘要

PURPOSE: A digital picture quality improving method and apparatus are provided to automatically improve contrast in adaptation for document images having various characteristics. CONSTITUTION: A parameter Vb for obtaining a reference variable X1 used for judging a dark background region, a parameter Vp for obtaining a reference variable X2 used for judging a bright background region, and initial values of the X1 and X2 are set(S10). RGB color data of an object pixel is converted to value data Xij and saturation data(S20). The size of Xij is compared with the size of Vb to re-set the Vb, and the size of Xij is compared with the size of Vp to re-set the Vp(S30). A background region that requires contrast improvement is detected through comparison of the Xij and X1 and X2, and contrast is improved for pixels belonging to the background to obtain improved value data Yij(S40). The value data Yij and the saturation data are converted to RGB color data(S50). It is judged whether the object pixel is a final pixel of an object line(S60). When the object pixel is the final pixel of the object line, the X1 is updated using the Vb and the X2 is updated using the Vp(S70).