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　　调频网点(Frequency Modulated HalftoneDot，简称FM网点)的出现及它在解像力、无龟纹及文合一处理等方面的优势，受到印刷界的普遍重视。随着材料和配套工艺的完善，将成为一种优于传统调幅网点(Amplitude Modulated Halftone Dot，简称AM网点)的主要加网方式。
　　常规加网技术用改变网点大小的方法来再现连续调原稿的颜色和层次变化，改变网点的大小相应于无线电技术中的幅度调制，由于这一原因，调频加网技术出现后人们将常规加网技术产生的网点称为调幅网点。
　　调频网点技术与调幅网点技术的不同，在于它不是通过改变网点大小的方法，而是由计算机按数字图像的像素值产生大小相同的点，这些点的最小直径可与设备的记录精度相等。一个半色调单元中有限个点群的集合构成了形式上很特殊的网点，它没有固定的形状，这些点出现的位置是随机的，又被称为“随机网点”，例如两个数值上完全相等的像素在采用调频加网技术形成网点时，虽然记录点的数量相同，但出现位置却不同。构成一个调频记录点面积的总和等于一个常规网点的大小，它的面积率也与常规网点相等。调幅网点是以网点的大小来表示图像的色调效果，网点在空间出现的频率和单位面积上网点的数量恒定不变，通过改变网点面积来表现图像色调，即亮调部位网点小，暗调部位网点大；调频网点面积固定不变，靠改变网点在空间的分布密度(密集程度)来表现图像色调。
　　调频网点与调幅网点相比较具有很多优点，主要表现在：
　　1．消除“龟纹”的产生。彩色印刷通常利用四种独立的加网图像准确套印而完成的，这些图像分别使用青、品红、黄和黑四色油墨印刷，采用调幅加网技术，规则的有序排列的网点和网点的单一化，必然产生网线角度，在套印过程中不可避免地产生“龟纹”。而调频加网技术，网点出现的概率是随机的，网点排列是无规律的，不再有规则的空间网点状结构，消除了由于图像本身某些规则条纹与加网网屏发生干涉而产生“龟纹”的可能性。
　　2．提高色彩复制能力。由于调频网点分布不规则，不存在网线角度问题，因此可采用青、品红、黄、 黑以外的颜色来扩大色域范围，增加专色油墨印刷，实现高保真(HiFi)色彩印刷，把印刷品和原稿的色彩差距减小，提高色彩的复制能力。
　　这对于印刷商用市场提高利润极有帮助。另外，由于调频网点作不规则分布，可避免网点相互重叠，油墨也可直接印在承印物上，故可使用较大的墨量，增加色彩效果。

　　3．解像力高。调频网点技术是网点的密集程度，即单位长度内网点的数量(DPL)表示网点图像的精细程度，构成FM网点的黑化点即是形成图像色调的“元素”，同时也是表现细微层次的最基本单元。在系统分辨率相同的条件下，调频网点比调幅网点具有更高的解像力。
　　4．高清晰度。在调幅加网技术中，网点线数决定清晰度，网线数越高，输出的网点面积越小，清晰度越好。但通常网线数过大，复制技术难度较大，所以调幅加网技术产生的输出图像都要做细微层次强调，即USM。由于调频加网采用的网点面积特别小，图像复制清晰度高，复制效果接近连续调的摄影稿，特别是亮调和暗调部位细微层次得到了很好的再现。在低分辨率的照排机上采用调频网点技术也可获得高质量的图像，而调幅网点技术对照排机的分辨率要求较高。

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同城: 未知

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