A tone-mapping method for adjusting a contrast of an image includes generating a luminance histogram of the image according to a luminance and a sharpness of the image; performing histogram equalization on the luminance histogram, to generate a luminance mapping function corresponding to the image; performing a weighted operation on the luminance mapping function and a linear function, to generate a weighted luminance mapping function corresponding to the image; generating a tone-mapping look-up table corresponding to the image according to the weighted luminance mapping function; and adjusting the luminance of the image according to the tone-mapping look-up table, so as to adjust the contrast of the image.