A three-dimensional display device comprises a flat display panel and an image-converting sheet disposed on or above the display panel. The display panel comprises a matrix of unit display cells arranged as rows and columns and where the cells are spaced apart to have respective row and column direction pitches. The image-converting sheet comprises a plurality of inclined lenticular lenses where the inclination is set according to the row and column direction pitches so as to reduce perception of Moiré patterns when stereo-scopic images are projected through the image-converting sheet to an observer viewing the display panel as an upright panel having respectively different left and right stereo-scopic image projections.