Sharp Kabushiki Kaisha Corporation

Osamu Mamba

Daisuke Koyama

Koji Otsuka

Yasufumi Hagiwara

Power consumption is cut down by reducing backlight light source luminance in accordance with the variability of luminance of the picture displayed on a display panel. A picture luminance detector calculates information (luminance information) representing luminance of the picture at intervals of a time unit. A picture luminance storage is a memory capable of storing the past records of luminance information within a fixed period of time (some seconds to some ten seconds). A processor is configured of a variation detector and a light source luminance determiner. Variation detector performs detection of the variability of picture luminance based on the luminance information on the current picture detected by picture luminance detector and the past records of picture luminance information stored in picture luminance storage to output variation information. Light source luminance determiner determines light source luminance based on the luminance information on the current picture detected by picture luminance detector and the variation information output from variation detector and outputs a light source information control signal.

Luminance control device, display apparatus using the same, luminance control method and luminance control program

The fact that B and R are close to a U axis and to a V axis, respectively, is noted. On that basis, from an example of color adjustment parameters set in directions of colors, it is found out that, when inputted V is in a negative range, B has a small influence. Accordingly, a B component is omitted from calculation in order to reduce a calculation amount. Similarly, components having small influences are omitted when B is in a positive range, when U is in the positive range, and when U is in the negative range. Thereby, adjustment parameters A, A, and Aset in directions shown in the drawing can be defined. When inputted V is in the positive range, a V component can be adjusted by multiplying Aby the inputted V. Similar processing is performed when inputted V is in the negative range, when U is in the positive range, and when U is the negative range, respectively. With this taken into consideration by setting values of the adjustment parameters for respective RGB larger than 1 or smaller than 1, color transformation processing for adjusting darkness/lightness of colors can be performed, independently of brightness, so as to bring values of U and V close toward a color component to be increase in intensity. This allows reduction in load of color transformation processing.

Color adjustment circuit

Shown is a diagram showing input-output characteristics for color adjustment. The horizontal axis represents an input, and the vertical axis represents an output. In this color adjustment technique, first, so as to prevent degradation the luminance of white after white correction, correction coefficients are determined so that the smallest value thereof may be 1. Note that '1' here is not a strict value. To be more specific, in contrast to the conventional technique in which correction is performed with the largest value being made equal to about '1,' the present embodiments sets the smallest value at about &#x201c;1.&#x201d; This idea itself is a first point which makes the embodiments different from the conventional technique. When doing so, all the correction coefficients are &#x201c;1&#x201d; or larger. In the case where a correction coefficient is &#x201c;1&#x201d; or larger, when the input is large, the output is saturated. To prevent the saturation, the saturation suppressed using an n-degree curve (X) which is, for example, a quadratic curve or a cubic curve. If doing so, degradation in the maximum luminance due to correction processing can be suppressed while the hue of white is maintained in a practical luminance range (0 to 70%) for video images of a television receiving set (TV), or the like. Thereby, degradation in the maximum luminance due to correction processing can be suppressed while the hue of white is maintained.

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Osaka, Japan

Osamu Mamba