1. An image display panel, comprising a histogram generator, receiving an original image, counting the pixels of different gray levels to generate a histogram distribution of the original image, and comparing the pixel counts at every gray level with a first threshold count to identify the peaks of the histogram distribution; a tone slope generator, generating a tone slope based on the histogram distribution and the peaks of the histogram distribution; and an image transformer, transforming the original image into a modified image based on the tone slope wherein the tone slope generator comprises: a sectionalizing unit, determining a plurality of reference gray levels and, for each of the reference gray levels, determining a first gray level section in which the gray levels are less than the reference gray level and a second gray level section in which the gray levels are greater than the reference gray level; a contrast improver, generating a modified reference gray level for each of the reference gray levels, and setting the modified reference gray level to be greater than the corresponding reference gray level when the pixel count in the corresponding first gray level section is greater than the pixel count in the corresponding second gray level section and setting the modified reference gray level to be less than the corresponding reference gray level when the pixel count in the corresponding first gray level section is less than the pixel count in the corresponding second gray level section; a noise reducer, moving the modified reference gray level toward the corresponding reference gray level when there is at least one peak in the corresponding first and second gray level sections; and an interpolator, generating the tone slope to map the reference gray levels to the corresponding modified reference gray levels.