IMAGE PROCESSING USING CONTENT-BASED WEIGHTED DITHERING

摘要

Image processing transforms input multi-level image data into output image data having a smaller number of levels (the input and output image data represents images formed of cells). The image processing distributes quantization error of a target cell of the image to neighbour cells in proportions determined by a set of weights. The distribution excludes neighbour cells whose data level is less than a threshold value from receiving distributed quantization error, or allows just a fraction of the quantization error to be distributed to such neighbour cells.

主权项

1. An image processing method transforming input multi-level image data into output image data having a smaller number of levels, wherein the input and output image data represent images formed of cells, the method comprising:
quantizing the input image data according to said smaller number of levels, evaluating quantization error produced during the quantizing, and distributing the quantization error evaluated for a target cell of the image to a set of neighbor cells in the vicinity of the target cell, in proportions determined by a set of weights, wherein the set of weights is determined by adjusting a predetermined weighting distribution which assigns predetermined weights to neighbour cells of said set according to their positions relative to the target cell, and the adjusting comprises reducing, below the predetermined value assigned to the corresponding cell position, the weights assigned to neighbor cells of said set whose data level is less than a threshold value.