今年早些时候，我发布了一个利用冷套印效果,so today I thought I'd talk a little about the process of using overprint in creative ways in your own print design projects.Read on to find out what overprint is and how you can use this technique to produce colourful overlapping effects in your prints.
每当你为印刷品设计的时候，by default your design software automatically sets your elements to "knock out"the artwork below.如果不这样做，all the colours of your design would be printed on top of each other and result in a muddy mess!然而，我们可以把一种颜色直接印在另一种颜色上，以达到特定的目的。
One such purpose of overprinting is to eliminate the chance of "ghosting".This is when the print plates are slightly misaligned and cause a thin outline to appear around text that is knocked out from a background colour or photograph.Rather than having the printer punch out the shape of the text from all the separations,您可以将其设置为套印，直接在其他颜色的顶部打印。
Overprinting is also a really handy technique when you're working on a print with limited colours.你可以把两种颜色混合在一起产生第三种颜色，which provides opportunities for creating really cool overlapping artwork.
Overprint vs Multiply (or Darken)
套印是打印文件中的一种规格，用于将某些颜色与墨水混合，whereas Multiply and Darken are transparency modes in your design software that mimic effects similar to overprint.The main difference between these settings is the overprint effect won't be visible unless you turn on Overprint Preview in your document,因为毕竟，它是一个印前特征，而不是一个设计特征。
如果在青色方块上重叠洋红色方块并将其设置为套印，Multiply or Darken you'll see the same result.Illustrator和InDesign使用与套印设置类似的规则在打印文件中导出这些效果，意味着这些元素不会被“淘汰”。然而，keep in mind there are some differences between these modes.
Change all the magenta squares to blue,然后将填充百分比降低到50%。套印和变暗配置仍然相同，但乘法版本有一个较暗的重叠区域。把重叠方块的填充量减少到25%，事情就会变得更加混乱！The Overprint and Darken examples are now completely different.
It's always worth checking the separations in Adobe Acrobat using the Output Preview tool to make sure your elements aren't being knocked out.此功能确认“倍增”和“变暗”的复制方式与“套印”相同，but I have heard that same print rips don't like these blending modes.To be safe I'd recommend using the proper Overprint method whenever you're going for an overprint style effect.
How to create effects with Overprint
We've already seen how Overprint can be used to mix two colours to create a third.This technique can be used to create cool print effects where two different types of artwork are overlapped.It's especially useful if you're working with a limited selection of Pantone colours.
You'll find the option to set an element to Overprint in the Attributes panel.Don't forget to turn on Overprint Preview under the View menu to simulate the effect,否则看起来不会有什么变化。
当你把你的作品输出打印时，潜在的问题仍然存在。默认情况下，打印为PDF或PostScript选项设置为“保留”the Overprint settings,但当你查看PDF文件时，它们实际上并没有显示效果。
Under the Advanced options in the Print settings change the Overprint and Transparency Flattener option to "Simulate"to allow your PDF to show the full overprint effect.或者，you can view the "Preserve"在Acrobat的输出预览工具中选中“模拟套印”选项时套印效果。
The requirement that you turn on simulated overprinting at the design and prepress stage can be a real risk when it comes to having your art professionally printed,所以，一定要与你选择的印刷公司彻底沟通你的愿望。As we've seen though,the Multiply and Darken blending modes perfectly simulate the overprint effect,因此，在基于网络的图形或基本的数字打印中，伪造它要容易得多。