Multi-half-tone imaging and dual modulation projection/dual modulation laser projection
Smaller halftone tiles are implemented on a first modulator of a dual modulation projection system. This techniques uses multiple halftones per frame in the pre-modulator synchronized with a modified bit sequence in the primary modulator to effectively increase the number of levels provided by a given tile size in the halftone modulator. It addresses the issue of reduced contrast ratio at low light levels for small tile sizes and allows the use of smaller PSFs which reduce halo artifacts in the projected image and may be utilized in 3D projecting and viewing.
1 . A method for dual modulation display, comprising:
determining a correction factor from a Point Spread Function (PSF) associated with relay optics of the dual modulation display, wherein the PSF is larger than a smallest feature that can be obtained from a halftone conversion of uncorrected pre-modulator image data, and wherein the feature is a spacing of non-zero pixels of the halftone conversion,
applying the correction factor to the uncorrected pre-modulator image data to be sent to a pre-modulator to generate corrected pre-modulator image data; and
energizing the pre-modulator with the corrected pre-modulator image data, the corrected pre-modulator image data including a convolution of a low-resolution version of an image produced by a primary modulator and the correction factor,
wherein the primary modulator receives light from the pre-modulator, wherein the corrected pre-modulator image data is a halftone image changed at least three times per frame of the pre-modulator, wherein energization signals used to energize the primary modulator are changed at least one time per frame of the primary modulator, and wherein energizing the pre-modulator with the corrected pre-modulator image data is synchronized with energization signals used to energize the primary modulator to provide an average of the halftone image and the image produced by the primary modulator.
2 . The method of claim 1 , further comprising:
illuminating the pre-modulator by a light source.
3 . The method of claim 1 , wherein applying the correction factor further comprises applying the correction factor during the at least three halftone images per frame of the pre-modulator.
4 . The method of claim 3 , wherein applying the correction factor during multiple halftones per frame of the pre-modulator is synchronized with a modified bit sequence in the primary modulator to produce a compensation image.
5 . The method of claim 3 , wherein applying the correction factor during multiple halftones per frame of the pre-modulator further comprises applying the correction factor during a single frame period of a modulation period of the primary modulator and several sub-frame time periods of a modulation period of the pre-modulator.
6 . The method of claim 5 , wherein pixel elements of the primary modulator are switched on/off once during the single frame period and pixel elements of the pre-modulator are switched on/off once during a single sub-frame period and further that the single frame period comprises a plurality of sub-frame time periods.
7 . The method of claim 1 , wherein the corrected pre-modulator image data includes a left image and a right image of three-dimensional image.
8 . The method of claim 1 , wherein the halftone image is changed at least four times per frame of the pre-modulator.
9 . The method of claim 1 , further comprising:
limiting a percentage of non-zero pixels.