Plasma display device and processing method thereof

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 a first image signal to a second image signal and expresses the second image signal by a real part and an error part to avoid use of a specific subfield lighting pattern;
• an error diffusion circuit which, when the error part of the second image signal is not zero, spatially or temporally diffuses the error part;
• and
• a subfield pattern conversion circuit which, when a lighting pattern of the subfields is selected based on the error-diffused second image signal, selects another subfield lighting pattern without using the specific subfield lighting pattern.