1. A system of image correction, utilized to receive an image and produce a revised image, comprising: an image acquisition unit, configured to receive the image, the image comprising a plurality of pixels, each pixel comprising a pixel value corresponding to one of a plurality of color-scale values; a distribution calculation unit, configured to calculate a frequency value for each of the color-scale values, representing how many pixels in the image correspond to each of the color-scale values; a potential range calculation unit, configured to acquire a color-scale threshold by limiting summation of frequency values from the brightest end to the color-scale threshold being the minimum value exceeding or equaling a ratio of pixels, and acquire a lower color-scale limit and an upper color-scale limit by respectively adding and subtracting a range value to and from the color-scale threshold; a weighted value calculation unit, configured to acquire a weighted value for pixels with the pixel values between the lower color-scale limit and the upper color-scale limit; and an image correction unit, configured to replace the pixel values between the lower color-scale limit and upper color-scale limit with the weighted value, thereby generating the revised image.