Image display apparatus for correcting dynamic false contours
View Patent ↗An image display apparatus, such as a plasma display panel, suppresses dynamic false contours with gradation levels sufficiently retained. The image display apparatus has agitation constant adder for generating a plurality of agitation constants for a gradation level corresponding to an image signal, for selecting one agitation constant therefrom, and for adding the agitation constant to the image signal. As a result, dynamic false contours can not be visually perceived because their portions are dispersed by superimposing an agitation to each image signal.
1. An image display apparatus, which forms fields each comprising a plurality of subfields and displays a multilevel gradation by controlling each of the subfields to be emitted or non-emitted, comprising:
an agitation adder for adding an agitation constant to an image signal, the agitation adder including:
an agitation constant generator for generating at least four agitation constants for each gradation level, the at least four agitation constants independently generated based on each gradation level in a plurality of arrangements for each gradation level corresponding to the image signal;
an agitation constant selector for selecting one agitation constant out of the at least four agitation constants arranged in the plurality of arrangements based on a configuration of the plurality of subfields of each field; and
an adder for adding the agitation constant selected by the agitation constant selector, to the image signal.
2. An image display apparatus as claimed in claim 1 , wherein a sum of the at least four agitation constants for each arrangement is zero.
3. An image display apparatus as claimed in claim 1 , wherein at least one of the agitation constants is approximately 20% of the gradation level for each of the gradation levels and at least another one of the agitation constants is approximately 10% of the gradation level for each of the gradation levels.
4. An image display apparatus, which forms fields each comprising a plurality of subfields and displays a multilevel gradation by controlling each of the subfields to be emitted or non-emitted, comprising:
a gradation-level limiter for limiting an image signal to a plurality of gradation levels, and for diffusing a difference caused by the limiting as a display error, to a surrounding pixel; and
an agitation adder for adding an agitation constant to an image signal limited by the gradation-level limiter, the agitation adder including:
an agitation constant generator for generating at least four agitation constants for each gradation level, the at least four agitation constants independently generated based on each gradation level in a plurality of arrangements for each gradation level corresponding to an image signal limited by the gradation-level limiter;
an agitation constant selector for selecting one agitation constant out of the at least four agitation constants arranged in the plurality of arrangements based on a configuration of the plurality of subfields of each field; and
an adder for adding the agitation constant selected by the agitation constant selector, to the image signal.
5. An image display apparatus as claimed in claim 4 , wherein a sum of the at least four agitation constants for each arrangement is zero.
6. An image display apparatus as claimed in claim 4 , wherein at least one of the agitation constants is approximately 20% of the gradation level for each of the gradation levels and at least another one of the agitation constants is approximately 10% of the gradation level for each of the gradation levels.