A color image is compressed by associating a variable length color code with each color of the original colour image, and then forming bitplanes each representing one bit position of the binary color codes for each pixel of the color image. The electro-optic material includes a non-polar solvent and a polar solvent dispersed in the non-polar solvent and controlled by the electric field. The major groove segments incline at an angle of from 5 to 30 degrees with respect to the tire circumferential direction.