An LCD that can show colors must have three subpixels with red, green and blue color filters to create each color pixel. Through the careful control and variation of the voltage applied, the intensity of each subpixel can range over 256 shades.
Color displays take an enormous number of transistors.
For example, a typical laptop computer supports resolutions up to 1,024 by 768. Most active matrix displays have a few bad pixels scattered across the screen. LCD technology is constantly evolving. Display size is limited by the quality control problems faced by manufacturers. Simply put, to increase display size, manufacturers must add more pixels and transistors.