An image processing method for reducing a power consumption. The image processing method may reduce the power consumption by classifying an input content into a conversion target region and a preservation target region and by converting a luminance of pixels included in the conversion target region. Also, the image processing method may effectively perform a luminance conversion for pixels by separating the input content into the conversion target region and the preservation target region based on a luminance of the pixels of the input content. The image processing method may convert the luminance of the pixels of the conversion target region to maintain a contrast between text pixels and background pixels.