Patent ID: 8027059

Claim:
An image processing device comprising: a storage unit that stores a color image having ground color and different color from the ground color, the color image being formed by color-pixels including a ground color pixel and a different color pixel, the ground color pixel having the ground color, the different color pixel having the different color; a first processing unit that produces a first gray-scale image from the color image, the first gray-scale image having fewer pixels when compared to the color image and is represented by brightness having a plurality of brightness values, the first gray-scale image being formed by first gray-scale pixels; a second processing unit that produces a histogram of the first gray-scale image, the histogram showing a distribution of the color pixels with respect to the brightness; a first determination unit that determines a first threshold level of the brightness based on the histogram; and a first replacement unit that compares a brightness value of at least one of the color pixels with the first threshold level to detect the ground color pixel and replaces the detected ground color pixel with a white color pixel to produce a processed color image, the white color pixel having white color.