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Gray-scale image created for threshold sequencing methods and the gradation image data creating apparatus
Gray-scale image created for threshold sequencing methods and the gradation image data creating apparatus
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机译:为阈值排序方法创建的灰度图像和灰度图像数据创建设备
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摘要
A threshold arrangement capable of reducing a moiré pattern produced by an interference between the output resolution and halftone frequency of an image outputting apparatus is determined. Halftone dot image data is generated by a threshold arrangement determined up to a certain gradation, and low-frequency component data is extracted from the halftone dot image data by an FFT, a LPF, and an IFFT. The position of a threshold where the extracted low-frequency component data is smaller is determined as the position of the threshold for a next gradation. The process of determining the position of the threshold is a process in a real space, and can determine the position of the threshold for the next gradation accurately. The threshold arrangement thus determined minimizes a moiré pattern which is an unwanted low-frequency component in a gradation image that is generated using the threshold arrangement.
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