Privacy-enhanced display device

• US 7,164,779 B2
• Filed: 08/06/2001
• Issued: 01/16/2007
• Est. Priority Date: 08/06/2001
• Status: Expired

• Current Assignee: Binary Services LLC (Intellectual Ventures LLC)
• Original Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Inventors: Yerazunis, William S., Leigh, Darren L., Carbone, Marco S.
• Primary Examiner(s): Wu; Jingge
• Assistant Examiner(s): GORADIA, SHEFALI DINESH
• Application Number:
  US09/923,107
• Publication Number:
  US 20030026449A1
• Time in Patent Office: 1,989 Days
• Field of Search: 345/533, 345537-538, 345501-502, 345/626, 345/8, 345/634, 345/641, 345/600, 345/690, 345/629, 382/100, 382/283, 382/284, 382/213, 382/214, 348/841, 348/661, 380200-242
• US Class Current: 382/100
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: G09G 5/00 Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators image data processing or generation, in general G06T

Abstract

A method displays an image only to an authorized user by generating a mask image from a data image. The data and mask image are then displayed periodically in an alternating manner on a display device by a select signal. The opening end shutting of an optical shutter device is synchronized to the displaying of the selected images so that only the data image is perceived by the authorized user viewing the display device through the optical shutter device, and a gray image is perceived by an unauthorized user viewing the data and mask images directly.

Claims

1. A method for displaying an image only to an authorized user, comprising:

generating a data image;

generating a mask image, from pixels of the data image, wherein the mask image is a negation of the pixels of the data image;

generating automatically a select signal with a controller;

selecting alternately the data image or the mask image according to the select signal; and

sequentially displaying the selected images on a display device to merge the data image and the mask image into a perceived continuous image to provide a perceived gray image to an unauthorized user while displaying the data image only to an authorized user.

2. The method of claim 1 further comprising:

opening an optical shutter device, according to the select signal, when the data image is displayed;

shutting the optical shutter device, according to the select signal, when the mask image is displayed so that only the data image is perceived by the authorized user viewing the display device through the optical shutter device, and the gray image is perceived by the unauthorized user viewing the data and mask images directly, the opening and shutting synchronized in phase and frequency to the select signal.

3. The method of claim 2 wherein the optical shutter device includes a polarizing lens on either side of a ferro-electric liquid crystal polarization rotator.

4. The method of claim 2 further comprising:

synchronizing the displaying, and the opening and shutting by a wire link.

5. The method of claim 2 further comprising:

synchronizing the displaying, and the opening and shutting by a wireless link.

6. The method of claim 5 wherein the synchronization is according to a phase of the select signal.

7. The method of claim 2 further comprising:

generating a first random select signal to select the displayed images;

generating a second random select signal to open and shut the optical shutter device; and

synchronizing the second random select signal to the first random select signal.

8. The method of claim 1 wherein each image is a color image, and the negation is done independently for each color channel of the color image.

9. The method of claim 8 further comprising:

gamma-correcting each color channel after the negation.

10. The method of claim 8 wherein each input pixel of each color image has an intensity in a range from 0 to 255, and each output pixel is determined by:

output=255((input/255)^1/γ

)+0.5.

11. The method of claim 1 wherein the select signal is generated by a clock, and further comprising:

alternately selecting the data and mask images according to clock cycles.

12. The method of claim 1 wherein the select signal is generated by a random generator of the controller.

13. The method of claim 12 wherein the displayed images occur in pairs so that each pair includes a first image and a second image in a random order.

14. The method of claim 12 wherein the random generator operates according to an internal seed value and a real-time supplied value.

15. The method of claim 1 wherein each data image includes a plurality of pixels, and further comprising:

negating each pixel of the data image serially to generate each corresponding pixel of the mask image; and

serially selecting each pixel of the data image or the mask image according to a select signal; and

sequentially displaying the selected pixels on a display device.

16. The method of claim 15 further comprising:

opening an optical shutter device when the selected pixel of the data image is displayed;

shutting the optical shutter device when the selected pixel of the mask image is displayed so that only the data image is perceived by the authorized user viewing the display device through the optical shutter device, and a gray image is perceived by the unauthorized user viewing the data and mask images directly, the opening and shutting synchronized in phase and frequency to the select signal.

17. The method of claim 16 wherein the select signal is generated by a clock, and further comprising:

alternately selecting the pixel from the data and the pixel from the mask images according to clock cycles of the controller.

18. The method of claim 1 wherein the select signal is generated by a random generator of the controller.

19. The method of claim 1 wherein a plurality of data images are provided in a video, and each data image is sequentially negated to produce the corresponding mask image.

20. An apparatus for displaying an image only to an authorized user, comprising:

a video camera generating a data image;

an inverter for generating a mask image from pixels of the data image, wherein the mask image is a negation of the pixels of the data image;

a controller generating automatically a select signal for selecting alternately the data image or the mask image; and

a display device for sequentially displaying selected images as a merged perceived continuous image on a display device to produce a perceived gray image and while displaying the data image only to an authorized user.

21. The apparatus of claim 20 further comprising:

an optical shutter device opened when the data image is displayed and closed when the mask image is displayed so that only the data image is perceived by the authorized user viewing the display device through the optical shutter device, and a gray image is perceived by the unauthorized user viewing the data and mask images directly, the opening and shutting of the optical shutter device synchronized in phase and frequency to the select signal.

22. The apparatus of claim 20 wherein the data and mask images are selected periodically by the automatically generated select signal.

23. The apparatus of claim 20 wherein the data and mask images are selected randomly.

24. The apparatus of claim 20 wherein each image includes a plurality of pixels, and wherein each pixel of the data image negated serially.