Automatic luminance and contrast adjustment as functions of ambient/surround luminance for display device

• US 6,529,212 B2
• Filed: 08/28/2001
• Issued: 03/04/2003
• Est. Priority Date: 11/14/1997
• Status: Expired due to Term

• Current Assignee: Monument Peak Ventures, LLC (Dominion Harbor Enterprises, LLC)
• Original Assignee: Eastman Kodak Company
• Inventors: Niederbaumer, James R., Miller, Michael E.
• Primary Examiner(s): Bella, Matthew C.
• Assistant Examiner(s): BLACKMAN, ANTHONY J
• Application Number:
  US09/940,999
• Publication Number:
  US 20020024529A1
• Time in Patent Office: 553 Days
• Field of Search: 345/690, 345/102, 348/602, 348/603, 348/222, 348/227
• US Class Current: 345/690
• CPC Class Codes: B60K 2360/349 Adjustment of brightness
• CPC Class Codes: B60K 2370/349 Adjustment of brightness
• CPC Class Codes: G09G 2320/0606 Manual adjustment
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/066 for control of contrast
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 5/10 Intensity circuits

Abstract

An apparatus and method is provided for dynamically modifying both the luminance and contrast of an image as it is displayed on a display unit in response to changing lighting conditions. Sensors are utilized to continually measure the luminance of the light illuminating the display unit and the display surround luminance. Measurement signals generated by the light sensors are processed to provide display luminance and contrast adjustment control signals that gradually cause the adjustment of the display unit'"'"'s luminance and contrast in response thereto. Continual adjustment of the luminance and contrast of a display unit according to changing lighting conditions such that the brightness and contrast perception of the displayed image remains constant under the varying conditions. As a result, a number of advantages our obtained including: the brightness and contrast perception of images displayed on a display unit remains constant as the display device illumination changes; the brightness and contrast perception of images displayed on a display unit remains constant as the display unit surround luminance changes; and power consumption is decreased in dim environments.

Claims

1. An apparatus for automatically controlling a display luminance and contrast of a display device, the apparatus comprising:

a) an illumination measuring mechanism for measuring a display illumination of a display device;

b) a surround luminance measuring mechanism for measuring a surround luminance of an area which surrounds the display device;

c) a calculating mechanism for calculating a current display luminance and a current contrast setting for the display device;

d) a determining mechanism for determining a change in the display illumination and a change in the surround luminance based on measurements performed by the illumination measuring mechanism and the surround luminance measuring mechanism, respectively;

e) a luminance adjustment mechanism for calculating an updated display luminance when the determining mechanism determines that a change in the display illumination has occurred, and for adjusting the display luminance of the display device based on the updated display luminance to display an image; and

f) a contrast adjustment mechanism for calculating an updated image contrast when the determining mechanism determines that a change in the surround luminance has occurred, and for adjusting the image contrast on the display device based on the updated contrast setting to display the image;

wherein the current display luminance is replaced with the updated display luminance and the current contrast setting is replaced with the updated contrast setting; and

wherein the luminance adjustment mechanism calculates the updated display luminance based on the change in display illumination, and further performs a progressive time dependent adjustment of the display luminance based on whether the updated display luminance is higher or lower than the current display luminance.

2. An apparatus as claimed in claim 1, wherein the determining mechanism calculates the current display luminance based on a determination of whether an initial display illumination measured by the illumination measuring mechanism is different from a default display illumination stored in memory.

3. An apparatus as claimed in claim 1, wherein the determining mechanism calculates the current contrast setting based on a determination of whether an initial surround luminance measured by the surround luminance measuring mechanism is different from a default surround luminance stored in memory.

4. An apparatus comprising:

a) imaging means for generating electronic image data corresponding to an imaged scene;

b) a display means for displaying the electronic image data generated by the imaging means;

c) illumination measuring means for measuring a display illumination of a display device;

d) surround luminance measuring means for measuring a surround luminance of an area around the display device; and

e) control means for controlling a display luminance and contrast of the display means, wherein said control means includes;

i) calculating means for calculating a current display luminance and a current contrast setting for the display device;

ii) determining means for determining a change in the display illumination and a change in the surround luminance based on measurements performed by the illumination measuring means and the surround luminance measuring means, respectively;

iii) luminance adjustment means for calculating an updated display luminance when the determining means determines that a change in the display illumination has occurred, and for adjusting the display luminance of the display device based on the updated display luminance to display an image; and

iv) contrast adjustment means for calculating an updated contrast setting when the determining means determines that a change in the surround luminance has occurred, and for adjusting the contrast of the display device based on the updated contrast setting to display the image;

wherein the current display luminance is replaced with the updated display luminance and the current contrast setting is replaced with the updated contrast setting; and

wherein the luminance adjustment means calculates the updated display luminance based on the change in display illumination, and further performs a progressive time dependent adjustment of the display luminance based on whether the updated display luminance is higher or lower than the current display luminance.

5. An apparatus as claimed in claim 4, wherein the determining means calculates the current display luminance based on a determination of whether an initial display illumination measured by the illumination measuring means is different from a default display illumination stored in a memory.

6. An apparatus as claimed in claim 4, wherein the determining means calculates the current contrast setting based on a determination of whether an initial surround luminance measured by the surround luminance measuring means is different from a default surround luminance stored in memory.

7. A method of controlling a display luminance and contrast of a display device comprising:

a) measuring a display illumination of a display device;

b) measuring a surround luminance of an area around the display device;

c) calculating a current display luminance and a current contrast setting for the display device;

d) determining a change in the display illumination and a change in the surround luminance;

e) calculating an updated display luminance when a change in the display illumination has occurred;

f) adjusting the display luminance of the display device based on the updated display luminance to display an image;

g) calculating an updated contrast setting when a change in the surround luminance has occurred;

h) adjusting the contrast of the display device based on the updated contrast setting to display the image; and

i) replacing the current display luminance with the updated display luminance and the current contrast setting with the updated contrast setting;

wherein the updated display luminance is calculated based on a change in display illumination, and a progressive time dependent adjustment of the display luminance is performed based on whether the updated display luminance is higher or lower than the current display luminance.

8. A method as claimed in claim 7, wherein the current display luminance is calculated based on a determination of whether a measured initial display illumination is different from a default display illumination stored in memory.

9. A method as claimed in claim 7, wherein the current contrast setting is calculated based on a determination of whether a measured initial surround luminance is different from a default surround luminance stored in memory.

10. An apparatus for automatically controlling a display luminance and contrast of a display device, the apparatus comprising:

a display illumination sensor adapted to measure a display illumination of a display device;

a surround luminance sensor adapted to measure a surround luminance of an area around the display device; and

a microprocessor adapted to;

calculate a current display luminance and a current contrast setting for the display device;

determine a change in the display illumination and a change in the surround luminance based on measurements performed by the display illumination sensor and the surround luminance sensor, respectively;

calculate an updated display luminance when it is determined that a change in the display illumination has occurred, and adjust the display luminance of the display device based on the updated display luminance to display an image; and

calculate an updated image contrast when it is determined that a change in the surround luminance has occurred, and adjust the image contrast on the display device based on the updated contrast setting to display the image;

wherein the current display luminance is replaced with the updated display luminance and the current contrast setting is replaced with the updated contrast setting; and

wherein the microprocessor is further adapted to calculate the updated display luminance based on the change in display illumination, and further performs a progressive time dependent adjustment of the display luminance based on whether the updated display luminance is higher or lower than the current display luminance.