Video display device and television receiving device with luminance stretching
Areas of a video signal that represent light emission are detected, the luminance levels at which said light emission areas are displayed are enhanced, emphasizing the areas, and the luminance stretching is controlled in accordance with the brightness of the surrounding environment, thereby increasing the resulting sense of brightness and improving the appearance of the video. A light emission detector counts pixels to generate a histogram of a prescribed feature quantity and identifies areas that fall within a prescribed range at the upper end of said histogram as being light emission areas. An area-active-control/luminance-stretching portion performs luminance stretching, increasing the luminance of a backlight portion and reducing the luminance of non-light emission areas of the video signal. The area-active-control/luminance-stretching portion switches between control curves, defining the relationship between the brightness-related index and the amount of stretching, in accordance with the brightness of the surroundings of the device.
1. An apparatus, comprising:
a display device displaying an input video signal;
a light source for illuminating the display device;
a brightness detector detecting brightness surrounding the apparatus; and
a processor and a storage device storing instructions that are operable, when executed by the processor, to cause the processor to control the display device and the light source including:
stretching and increasing luminance of the light source based on control curves that define a relation between an index associated with brightness calculated based on a predetermined condition from the input video signal and a luminance stretch quantity for stretching the luminance of the light source,
detecting a light emitting part that is regarded as a video emitting light based on a predetermined feature quantity of the input video signal, and enhancing display luminance of the light emitting part by reducing luminance of a video signal of a non-light emitting part excluding the light emitting part, and
switching the control curves according to the brightness surrounding the apparatus detected by the brightness detector
the processor and storage device storing further instructions that are operable, when executed by the processor, to cause the processor to:
divide an image by the input video signal into a plurality of areas, and change a corresponding lighting rate of the light source for each of the areas based on a tone value of a video signal of the divided area,
wherein the control curve is a control curve that defines a relation between an average lighting rate obtained by averaging the lighting rates corresponding to all areas and the luminance stretch quantity shown by possible maximum luminance on a screen of the display device, and
using the average lighting rate as the index associated with the brightness to stretch the luminance of the light source based on the maximum luminance defined in accordance with the average lighting rate.
2. The apparatus as defined in claim 1 , wherein
the processor and storage device storing further instructions that are operable, when executed by the processor, to cause the processor to:
perform video processing for outputting by converting an input tone of the input video signal,
wherein input/output characteristics that define a relation between the input tone and an output tone have a threshold that is defined in an area of a non-light emitting part having a lower tone than that of a boundary of the light emitting part and the non-light emitting part, and
predefine a relation between a gain applied to the video signal and the luminance stretch quantity, and determine a gain by which the output tone is reduced with respect to the input tone of the input video signal in accordance with the luminance stretch quantity and applies the determined gain to an area having a lower tone than the threshold to perform the video processing, and moves the threshold to a high-luminance side as the brightness detected by the brightness detection portion becomes darker in the video processing.
3. The apparatus as defined in claim 2 , the processor and storage device storing further instructions that are operable, when executed by the processor, to cause the processor to:
reduce an increment of display luminance of the display portion by stretching of the luminance of the light source through the video processing in a predetermined area having the low feature quantity.
4. An apparatus, comprising:
a display device displaying an input video signal;
a light source for illuminating the display device:
a brightness detector detecting brightness surrounding the apparatus; and
a processor and a storage device storing instructions that are operable, when executed by the processor, to cause the processor to control the display device and the light source including:
stretching and increasing luminance of the light source based on control curves that define a relation between an index associated with brightness calculated based on a predetermined condition from the input video signal and a luminance stretch quantity for stretching the luminance of the light source,
detecting a light emitting part that is regarded as a video emitting light based on a predetermined feature quantity of the input video signal, and enhancing display luminance of the light emitting part by reducing luminance of a video signal of a non-light emitting part excluding the light emitting part, and
switching the control curves according to the brightness surrounding the apparatus detected by the brightness detector, wherein
the control curve is a control curve that has the luminance stretch quantity which becomes smaller as the brightness detected by the brightness detection portion reduces.
5. A television receiving device including the apparatus as defined in claim 4 .
6. An apparatus, comprising:
a display device displaying an input video signal:
a light source for illuminating the display device;
a brightness detector detecting brightness surrounding the apparatus; and
a processor and a storage device storing instructions that are operable, when executed by the processor, to cause the processor to control the display device and the light source including:
stretching and increasing luminance of the light source based on control curves that define a relation between an index associated with brightness calculated based on a predetermined condition from the input video signal and a luminance stretch quantity for stretching the luminance of the light source,
detecting a light emitting part that is regarded as a video emitting light based on a predetermined feature quantity of the input video signal, and enhancing display luminance of the light emitting part by reducing luminance of a video signal of a non-light emitting part excluding the light emitting part, and
switching the control curves according to the brightness surrounding the apparatus detected by the brightness detector, wherein
the control curve is a control curve that defines a relation between a score obtained by counting the number of pixels by weighting brightness of each pixel and the luminance stretch quantity with respect to a video in a predetermined range including an area of the detected light emitting part, and
the processor and storage device storing further instructions that are operable, when executed by the processor, to cause the processor to:
use the score as the index associated with the brightness to stretch the luminance of the light source based on the score that is calculated from the input video signal.