| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an image reading device and an image forming apparatus that performs: generating a histogram, from image data read by plural line sensors, using a leading part of a manuscript; determining a threshold value based on the most frequent value in the histogram and a set mode setting a presence of a concentration difference in the manuscript; and performing binalization in accordance with the threshold value to acquire black/white image data. <P>SOLUTION: An image reading device performs: generating a histogram using a leading part of a manuscript, excluding a very leading portion, of read data obtained by plural line sensors arranged in a staggered pattern; determining a threshold value in accordance with a most frequent value in the generated histogram and a set mode that sets presence/absence of a concentration difference between a background portion and a character portion in the manuscript; storing image data read in advance in a image memory until the threshold value is determined; reading the image data from the image memory sequentially starting with a leading line in the manuscript after the threshold value is determined; and binarizing the image data to acquire black/white image data. The threshold value is displayed as a reference value after reading the manuscript, thereby the image data can be read again with any altered threshold value. <P>COPYRIGHT: (C)2012,JPO&INPIT |
