Automatic brightness control for displays
An automatic brightness adjustment for devices with displays includes the capability to assess ambient light. The assessment may be made using circuitry, such as a light meter circuit, by exploiting exposure control circuitry, or using other approaches. The ambient light value is sent to a brightness adjustment driver, which may employ a look-up table to keep track of brightness adjustments for particular ambient conditions. The look-up table may include distinct adjustment values.
1. A mobile apparatus comprising:
a display;
an imager to capture an image, provide an exposure for the image and adjust a brightness of the display, wherein said imager comprises a light sensor to detect an amount of light in a surrounding area, wherein the light sensor accumulates light energy over an integration interval to provide an indication of the amount of light; and
a processor to determine a perceived brightness value based on an equation whose value varies with the detected amount of light, wherein the equation comprises a factor that is a direct adaptation effect and a factor that is a lateral adaptation effect, and wherein conflicts between direct and lateral adaptations of a user's eye are to be avoided based on the perceived brightness value, wherein the lateral adaptation effect comprises a sum of weighted adaptations to spot luminances in proportion to their angular displacements from an axis of vision.
2. The apparatus of claim 1 , further comprising:
a look up table to translate the perceived brightness value to a display brightness setting.
3. The apparatus of claim 2 , wherein the look-up table is adaptable to a type of display being used.
4. The apparatus of claim 1 , wherein the display comprises a microdisplay.
5. The apparatus of claim 4 , wherein the microdisplay comprises one of a frontlit liquid crystal display (LCD), a backlit transmissive LCD or an organic light emitting diode (LED).
6. The apparatus of claim 1 , wherein the display comprises a direct view LCD.
7. The apparatus of claim 1 , wherein the imager comprises a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) device.
8. A mobile apparatus comprising:
a display;
an imager to capture an image, provide an exposure for the image and adjust a brightness of the display;
a light sensor to detect an amount of light in a surrounding area; and
a processor to determine a perceived brightness value based on an equation that provides a value that varies with the detected amount of light;
wherein the equation comprises:
B=AL 1/3 −S
where
A=100/(L AVG 1/3 +K),
S=100(ΣS i A i L i 1/3 ),
B is a perceived brightness in LUX,
A is a direct adaptation effect,
L, L i and L AVG are environmental luminances in cd/m 2 ,
K=3.6, and
S is a lateral adaptation effect comprising a sum of weighted adaptations to spot luminances in proportion to their angular displacement from an axis of vision.