| 摘要 |
An error diffusion process adds an error value to an input grey image value to produce a modified input grey image value before comparing the modified input grey image value with a predetermined threshold value. A rendering value and error is generated based on the comparison. An error equal to the modified input grey value is generated when the modified input grey value is less than the predetermined threshold value, and an error equal to the modified input grey value minus an effective spot area value is generated when the modified input grey value is equal to or greater than the predetermined threshold value. The effective spot area value is retrieved from a look-up table having a plurality of effective spot area values based on the input grey image value. The effective spot area values is created from a process of scanning a set of grey test patches corresponding to a set of known grey input values and generating image data therefrom, printing a set of grey patches based on the generated image data, measuring a reflectance of each grey test patch to generate a plurality of output grey values, one output grey value for each test patch and corresponding known grey input value, generating a tonal reproduction curve from the set of known grey input values and corresponding output grey values, calculating a plurality of effective spot area values, each effective spot area value being a result of dividing one output grey value by the corresponding known grey input value, and storing the plurality of effective spot area values as a function of the output grey value. The generated error is fractionalized and diffused to neighboring pixels.
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