{'fraction_non_alphanumeric': 0.02269170579029734, 'fraction_numerical': 0.005477308294209703, 'mean_word_length': 5.661458333333333, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
9.1: Frontal Projection‐type Three‐dimensional Display with Enhanced Brightness Uniformity

A method to uniformize the brightness of elemental image for the frontal projection‐type three‐dimensional (3D) display is proposed. A frontal projection three‐dimensional display which is possible to realize glasses‐free 3D display by combining a polarizing screen with a front projector has been proposed recently. This method uses a quarter‐wave retarding film (QWRF) and a polarizer with slits, and makes the audience see different directional views. This structure can change the polarization state orthogonally, so the image from projector is partially blocked when the image is reflected and meets the films. However, in this method, the quality of the reconstructed 3D image could be degraded since the light intensity at the barrier‐free regions of parallax barrier polarizer is brighter than that at the parallax barrier polarizer. We proposed two methods to relieve this difference, a parallax barrier rearrangement method and gray level compensation of illumination. By adopting two methods, we anticipate that the quality of reconstructed 3D image can be enhanced because of brightness uniformity in directional‐view images in the frontal projection‐type 3D display method.