Dynamic illumination control for laser projection display

1. A method for improving image contrast for a display apparatus comprising:

obtaining a frame of image data said image data comprising one or more code values for each pixel in the frame of image data;

analyzing the frame of image data to identify a distribution of dark regions therein;

adjusting at least one of the one or more code values for the frame of image data according to the distribution of dark regions in the frame of image data;

attenuating a brightness level available for the image frame according to the distribution of dark regions in the frame of image data; and

wherein the frame of image data includes a first portion and a second portion of image data from the frame and analyzing a distribution of dark regions within the first and second portions, adjusting at least one code value for each of the first and second portions, attenuating the brightness level of each of the first and second portions, and displaying the first and second portions of image data, wherein a brightness level attenuation for the second portion differs from the brightness level available for the first portion.

2. The method of claim 1 wherein analyzing the distribution of dark regions within the frame of image data comprises evaluating an image histogram.

3. The method of claim 1 wherein the frame of image data comprises the complete image.

4. The method of claim 1 wherein the frame of image data comprises a vertical or horizontal portion of the image.

5. The method of claim 1 wherein attenuating the brightness level comprises disposing an electro-optical modulator in the path of modulated light in the display apparatus.

6. The method of claim 1 wherein attenuating the brightness level comprises setting brightness to one of a set of fixed values.

7. The method of claim 1 further comprising attenuating output light after displaying the frame of image data.

8. The method of claim 1 further comprising displaying the frame of image data with the attenuated brightness level and adjusted code values.

9. The method of claim 1 wherein attenuating the brightness level applies the same attenuation to the entire image frame.

10. The method of claim 1 wherein attenuating the brightness level applies different attenuation over different portions of the image frame.

11. A method for improving image contrast for a display apparatus comprising:

obtaining a first frame of image data said image data comprising one or more code values for each pixel in the first frame of image data;

obtaining a second frame of image data said image data comprising one or more code values for each pixel in the second frame of image data;

analyzing the first and second frames of image data to identify a distribution of dark regions therein;

adjusting at least one of the one or more code values for the first frame of image data according to the distribution of dark regions in the first frame of image data and attenuating a brightness level available for the first image frame according to the distribution of dark regions in the first frame of image data;

adjusting at least one of the one or more code values for the second frame of image data according to the distribution of dark regions in the second frame of image data and attenuating a brightness level available for the second image frame according to the distribution of dark regions in the second frame of image data; and

attenuating the brightness level between display of the first and second image frames.