Plasma display device and processing method thereof

1. A display method of a plasma display device which expresses a gradation of an image by selecting a pattern of subfields to light up out of plural subfields composing one field, each of the subfields having a weighted number of sustain pulses, comprising:

nonlinearly converting first image data corresponding to an input image signal to second image data having a gradation value smaller than a gradation value of the first image data and expressing the second image data by a real part and an error part;

error diffusing of, when the error part of the second image data is not zero, spatially or temporally diffusing the error part; and

subfield pattern converting of selecting a lighting pattern of the subfields based on the error-diffused second image data,

wherein the second image data does not have image data corresponding to a predetermined subfield lighting pattern in which a temporal deviation of a temporal center of gravity of light emission depending on a lighting pattern between two subfields adjacent on a time base is larger than a mean value of temporal deviations of the temporal center of gravity of light emission among all subfields, and

wherein in said nonlinearly converting, in place of the image data, data calculated by interpolation using plural pieces of image data corresponding to plural subfield lighting patterns adjacent to image data corresponding to the predetermined subfield lighting pattern in the second image data is outputted.

2. The display method of the plasma display device according to claim 1 ,

wherein in data having a larger temporal deviation of a temporal center of gravity of light emission, a number of gradation values which are converted to the second image data

whose error part calculated by the interpolation in said nonlinearly converting is not zero is larger.

3. A display method of a plasma display device which expresses a gradation of an image by selecting a pattern of subfields to light up out of plural subfields composing one field, each of the subfields having a weighted number of sustain pulses, comprising:

nonlinearly converting first image data corresponding to an input image signal to second image data having a gradation value smaller than a gradation value of the first image data and expressing the second image data by a real part and an error part;

error diffusing of, when the error part of the second image data is not zero, spatially or temporally diffusing the error part; and

subfield pattern converting of selecting a lighting pattern of the subfields based on the error-diffused second image data,

wherein the second image data does not have image data corresponding to a predetermined subfield lighting pattern having gradation values prior to and subsequent to a gradation value at which a subfield with a larger weight first lights up when subfield lighting patterns are arranged in order of gradation value, and

wherein in said nonlinearly converting, in place of the image data, data calculated by interpolation using plural pieces of image data corresponding to plural subfield lighting patterns adjacent to image data corresponding to the predetermined subfield lighting pattern in the second image data is outputted.

4. The display method of the plasma display device according to claim 3 ,

wherein for a larger gradation value at which the subfield with a larger weight first lights up, a number of pieces of the image data corresponding to the predetermined subfield lighting pattern is larger.

5. A plasma display device, comprising:

a display unit which expresses a gradation of an image by selecting a pattern of subfields to light up out of plural subfields composing one field, each of the subfields having a weighted number of sustain pulses;

a nonlinear conversion circuit which nonlinearly converts first image data corresponding to an input image signal to second image data having a gradation value smaller than a gradation value of the first image data and expresses the second image data by a real part and an error part;

an error diffusion circuit which, when the error part of the second image data is not zero, spatially or temporally diffuses the error part; and

a subfield pattern conversion circuit which selects a lighting pattern of the subfields based on the error-diffused second image data,

wherein the second image data does not have image data corresponding to a predetermined subfield lighting pattern in which a temporal deviation of a temporal center of gravity of light emission depending on a lighting pattern between two subfields adjacent on a time base is larger than a mean value of temporal deviations of the temporal center of gravity of light emission among all subfields, and

wherein said nonlinear conversion circuit outputs, in place of the image data, data calculated by interpolation using plural pieces of image data corresponding to plural subfield lighting patterns adjacent to image data corresponding to the predetermined subfield lighting pattern in the second image data.

6. The plasma display device according to claim 5 ,

wherein in data having a larger temporal deviation of a temporal center of gravity of light emission, a number of gradation values which are converted to the second image data whose error part calculated by the interpolation by said nonlinear conversion circuit is not zero, is larger.