1. An image processing system for acquiring image data and processing the image data, the image processing system comprising: an acquiring unit configured to acquire the image data; a first determination unit configured to create one or more histograms of one or more colors in the image data acquired by the acquiring unit, and determine one or more deemed background colors with the use of the histograms; a second determination unit configured to determine a background color based on the deemed background colors determined by the first determination unit; a counting unit configured to count a number of pixels corresponding to one or more character colors in the image data, wherein colors other than the background color determined by the second determination unit are the character colors; and a deciding unit configured to obtain a ratio of the number of pixels corresponding to the character colors counted by the counting unit to a total number of pixels in the image data, and perform blank page determination on the image data by determining that the image data is blank when the ratio is less than a first predetermined value.