The invention relates to an imaging device, an image processing device and an image processing system, which aims to reduce the required processing time for the reading of manuscripts. The imaging device (100) generates a pattern image corresponding to information embedded in a medium, such as recording paper and the like. Then a transparent toner is coated on the recording paper medium coated with a colored toner according to the pattern image. The transparent toner is coated on some of dots coated with the colored toner in a dot coating manner. The area of dots coated with the transparent toner is smaller than the area of dots coated with the colored toner. The image reading device scans image data on the recording paper medium to obtain the pixel values of the image data, and then figures out the difference between the luminance values of adjacent pixels. When the difference between the luminance values of adjacent pixels is larger than a threshold value, the pixel of two adjacent pixels, which is lower in luminance value, is adopted as the part coated with the transparent toner.