Optimizing drive schemes for multiple projector systems
Light projection systems and methods may comprise combining light from two or more projectors, Each projector may be controlled so that the combined light output of the projectors matches a target for the projected light. In some embodiments optimization is performed to generate image data and control signals for each of the projectors. Embodiments may be applied in image projecting applications, lighting applications, and 3D stereoscopic imaging.
1. A method for displaying an image defined by image data using a system comprising a first projector and a second projector wherein the first projector has a lower dynamic range than the second projector and light from the first projector is combined with light from the second projector to yield a single displayed image, the method comprising:
processing the image data to determine black levels of the image and to simulate a veiling luminance to determine the lowest perceivable luminance level in the image;
if a black level of the first projector is greater than the black levels of the image, reducing a size of an iris in an optical path of the first projector to reduce a brightness of the first projector by an amount based on the black levels of the image, wherein the iris is positioned so light from the second projector does not pass through the iris;
controlling the first projector based on the determined black levels of the image to project parts of the image within the dynamic range of the first projector;
controlling the second projector based on the determined black levels of the image to supply highlights in the displayed image that have brightness greater than a peak brightness achievable by the first projector and to set the light level from the second projector at a level corresponding to the lowest perceptible luminance level.
2. The method according to claim 1 wherein reducing the brightness of the first projector comprises dimming a light source of the first projector.
3. The method according to claim 1 wherein reducing the brightness of the first projector reduces the peak brightness of the first projector and the method comprises computing the reduced peak brightness of the first projector.
4. The method according to claim 1 comprising adjusting the black levels of the image based on a level of ambient lighting.
5. The method according to claim 1 wherein simulating the veiling luminance is performed at a pixel level.
6. The method according to claim 1 comprising adjusting the black levels of the image based on a level of ambient lighting.
7. The method according to claim 1 wherein the processing further determines dynamic range and maximum luminance level of the image and the processing comprises generating modified image data based on the dynamic range, black levels and maximum luminance level.
8. The method according to claim 1 wherein reducing the brightness of the first projector comprises setting the brightness of the first projector such that with a spatial light modulator of the projector system in a least transmissive state, a brightness of the light contributed by the first modulator to the displayed image is equal to the black level of the image.
9. The method according to claim 1 wherein the processing comprises determining a peak brightness of the image and the method comprises not using the second projector in response to determining that the peak brightness of the image is below a peak brightness threshold and the black level of the image is below a black level threshold.
10. The method according to claim 1 comprising controlling the second projector to contribute light to regions of the image that have brightness lower than a peak brightness of the first projector.
11. The method according to claim 10 wherein the processing comprises portioning content of the image between the first and second projectors.
12. The method according to claim 11 wherein the processing comprises generating a mask of pixels in the image having brightness greater than the peak brightness of the first projector, blurring or diffusing the mask and controlling the second projector to contribute light to pixels corresponding to the blurred or diffused mask.
13. The method according to claim 11 wherein the processing comprises computing approximations of veiling luminance at each pixel of the image and adjusting parameters for blending light from the first and second projectors based on the approximations of veiling luminance.
14. The method according to claim 1 wherein the processing includes an “Adjust Black Level” operation which increases the black level of the image in cases where an observer would not be able to perceive the black level of the image.
15. The method according to claim 14 wherein the Adjust Black Level operation comprises applying a forward model of the projectors to predict halo in the displayed image.
16. The method according to claim 1 wherein the processing comprises generating from the image separate first and second image data for the first and second projector respectively and controlling the first projector comprises controlling the first projector to project the first image data and controlling the second projector comprises controlling the second projector to project the second image data.
17. The method according to claim 16 wherein the processing comprises using different gamma curves for the first and second projectors.
18. The method according to claim 16 wherein the processing comprises applying a blur to one of the first and second image data.