A method and apparatus for transforming color signals. The transformation is achieved by use of a first, coarse, look-up table and a second look-up table that provides coefficients to be used in calculating a correction vector. The vector of color components from the first look-up table is added to the correction vector to provide the transformed vector. The method and apparatus have particular application in the display of digital video signals.

A full color display optical system with chromatic aberration correction. The system includes a wide spectral band image source such as a cathode ray tube or Ferroelectric liquid crystal array, a field sequential Red-Green-Blue shutter, and an optical module for projection. The optical module corrects longitudinal chromatic aberration and higher order monochromatic and chromatic aberrations. Lateral chromatic aberration and chromatic distortion are compensated electronically by the color sequential shutter and the image source with a pre-distorted image.

An LCD device has a distorted and/or curved shape corresponding to an image formed on the screen before correcting for distortion and/or curvature of the image formed on the screen, which are generated due to distortion aberration and/or curvature aberration of the projection lens unit, so that distortion and/or curvature can be corrected. The LCD device has a pin-cushion type structure distorted and curved positively (+) so that negative (-) distortion and curvature of the image formed on the screen, which is generated due to distortion aberration and curvature aberration of the projection lens unit, can be corrected. Also, the LCD device includes a front substrate and a rear substrate, each having electrodes formed thereon, and the front substrate and/or the rear substrate have a pin-cushion shape distorted and/or curved positively (+). Thus, distortion aberration and/or curvature aberration of optical lenses of a projection lens unit can be corrected by appropriately correcting a light emitting point of image light.

For displaying moving images on a head mounted, temporal modulation display device from a video source, without image break-up appearing in the observed image, an image shift device is provided for shifting each temporally separated component image within each display cycle of grey scale component images representing each frame of the video source. The display device is for use with head mounted displays in which an LCD or other FPD using temporal modulation is used to display video images without image break-up during head motion.

A multiple focal distance light collecting optical device, is characterised in that it consists of a monoblock structure formed of at least a first and a second transparent material (8, 10) formed into lenses (12, 14, 16,) which are applied against and attached to each other the refractive indices and radii of curvature of the faces of such lenses being determined to focus the light rays so as to create an image in accordance with at least two different focal distances (A, B).