| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To accurately detect unwanted streaks in an image generated during printing of a document. <P>SOLUTION: An image analysis apparatus includes a step of detecting a luminance gradient direction of each of pixels constituting the image and its strength, based on Y (luminance) data of images of a document, respectively (S105). While switching a pixel to be defined as a pixel of interest sequentially over an entire screen, pixels being present within a predetermined region (e.g., a rectangular region of five pixels respectively in longitudinal and lateral directions) around the pixel of interest are then classified based on the luminance gradient direction of these pixels (S106). When the pixels within the predetermined region are classified eccentrically to a specific direction range group and there is considerable luminance fluctuation in the luminance gradient direction in the pixel of interest, the pixel of interest is determined as an edge pixel (S107). Further, based on a distribution density of pixels determined to correspond to the edge pixel, presence of unwanted streaks in the document is discriminated and moreover, a direction of the unwanted streaks is discriminated based on the luminance gradient direction of the edge pixels (S108). <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
