DISPLAY DEVICE FOR VISUALLY RECONSTRUCTING AN IMAGE

摘要

The invention relates to a display device for visually reconstructing an image (330) from an encoded image (320), such a device being particularly useful in the field of visual cryptography. The display device has two stacked liquid crystalline layers (410, 420) with individually addressable pixels. One layer (420) renders encoded image data together with a randomization pattern, and the other layer (410) only renders a randomization pattern. If the patterns match, the display device shows a visually reconstructed image (330) to a viewer. Means are provided for improving an optical match between the LC layers, such as a birefringent layer (414) between the two LC layers. Alternatively, two twisted nematic LC layers can be used having opposite twist directions. Such means were found to improve an image quality of the visually reconstructed image, and can in fact be advantageously applied in any display system including a plurality of LC layers cooperating for forming an image.