Patent ID: 6510252
Filing Date: 2003-01-21
Classification: H04N

Abstract:
An image processing method comprising the steps of:quantizing input image data of each pixel so as to convert the input image data into output image data assuming at least a minimum and a maximum level; selecting a weight coefficient for diffusing error, according to a gradation value of the input image data of each target pixels; and diffusing a quantization error, caused through quantization of target pixels in the step of quantizing, multiplied by the weight coefficient selected in the step of selecting weight coefficients, into input image data of unquantized pixels near each of target pixels; wherein the quantization error is modulated to the frequency band of a filter with a modulation characteristic according to the weight coefficient in the step of diffusing quantization error, and the weight coefficient is selected in the step of selecting a weight coefficient, so that the closer the gradation value of the input image data of a target pixel to either the minimum or the maximum quantization level in the step of quantizing, the more the modulation characteristic of the quantization error becomes three-dimensionally symmetrical with respect to the low frequency band of the filter.