预检: 如何避免印前PDF文件的十大常见问题

在发送印刷文件时,常见的错误包括叠印、错误的出血和RGB图像。捷克平面设计师和出版商Filip Blažek整理了一份印前注意事项,以节省您的时间、精力和金钱。
Overprinting, wrong bleed and RGB images are among usual mistakes when sending files to print. Czech graphic designer and publisher Filip Blažek has put together a preflight cheat sheet to save you time, hassle, and of course money.
作者:FILIP BLAŽEK
您已经设计了一些令人惊叹的东西,并且希望印刷机把它实现出来。送去印厂之前要将所有文件进行检查。这个过程被称为“预检”,可以为您节省很多麻烦,甚至是金钱。下面描述了印厂从客户那里接收文件时需要处理的十个最常见的问题。通过遵循这些简单的规则,您可以向印厂发送完美无瑕的数据,不用担心结果,而是享受一杯好咖啡或好茶。
BY FILIP BLAŽEK
You’ve designed something stunning and you want the printer to turn it into a real product. Now it’s time to check all documents before sending them to the printer. This process is called “Preflight” and can save you a lot of trouble and, yes, even money. The following list describes ten of the most common issues printing houses deal with when receiving files from their customers. By following these simple rules, you can send flawless data to a printer and, instead of worrying about the results, enjoy a good cup of coffee or tea.
Adobe InDesign和Affinity Publisher都提供了不错的预检工具。第一步是创建一个预检配置文件——一个你想要被警告的问题清单。然后,预检面板将显示文档中的所有潜在问题。不幸的是,默认的配置文件并不能指出每一个错误,但是一旦你定义了你自己的配置文件,它可以成为一个非常强大的工具。


Both Adobe InDesign and Affinity Publisher provide decent preflight tools. The first step is to create a preflight profile — a list of problems you want to be warned about. The Preflight panel will then display all potential problems within the document. The default profile unfortunately dose not point out every mistake, but once you define your own profile it can become a very powerful tool.
你也可以在Adobe Acrobat中检查你的PDF,它提供了一套广泛的印刷生产工具,包括输出预览和预检。尽管如此,不要仅仅依靠软件工具。用你自己的眼睛检查每一页是必不可少的!
You can also check your PDF in Adobe Acrobat, which offers an extensive set of Print Production Tools including Output Preview and Preflight. Nevertheless, don’t rely on software tools alone. Checking each page with your own eyes is essential!
用于在线分发的普通PDF文件不符合严格的专业印刷要求。因此,当把文件发送给专业打印店或胶印店时,请确保你发送的是可打印或可印刷的PDF。建议根据印刷行业标准之一导出PDF:选择PDF/X-1a或更新的PDF/X-4a。请查阅印厂的网站或咨询他们的业务人员。
Regular PDF files intended for online distribution do not match stringent professional printing requirements. So when sending files to professional digital or offset printing shops, make sure you are sending a print-ready or press-ready PDF. It is recommended to export PDFs according to one of the printing industry standards: select either PDF/X-1a or the newer PDF/X-4a. Consult the printers’websites to find their own requirements.
很简单。现在是你的文件发送前的细节。
Simple enough. Now the details before your files take flight.

1. 缺少出血
缺少出血设置可能是印刷时最常遇到的错误。出血的目的是确保你的对象到达页面的最边缘,而不会在边上留下任何白线。这一规则适用于所有元素:照片、插图、线和简单的彩色背景。始终检查放置在页面边缘的对象是否有出血设置,使它们超出每个页面边缘3毫米(0.125英寸)(共6毫米或0.25英寸)。
1. Missing bleed
The missing bleed is perhaps the most common mistake printers encounter. The purpose of the bleed is to make sure your objects reach the very edge of the page without leaving any white stripes on the side. This rule applies to all elements: photos, illustrations, rules, and simple colour backgrounds. Always check whether the objects placed on the edge of the page do have bleed, so they extend 3 mm (0.125″) beyond each page edge (total of 6 mm or 0.25 inches).
如图,在极少数情况下,当出血可能裁掉图像的重要部分时,你可以在Photoshop中使用图章工具补上缺失的出血量。
2. 对象的放置太靠近页面边缘
大多数印刷品在印刷后都会被裁切成最终尺寸。这是一个机械的过程,因此它是不精确的。如果您将文本框放置得离页面边缘太近,它可能会被部分裁切。同样的情况也适用于页面周围的细线:最终的结果可能导致每边的线宽略有不同。稳妥的做法,用激光切割可能是更好的选择,因为它更精确。
2. Objects placed too close to the page edge
Most printed matter is cut down to the final dimension after printing. It is a mechanical process and as such it is subject to impreciseness. If you place the text frame too close to the edge of the page, it can be partially trimmed. The same applies to thin lines around a page: the final result can lead to slightly different line widths on each side. For stationary, laser cutting might be a better option since it is more precise.

文字对齐页面边缘或非常窄的文本框会导致不尽人意的效果。左边的预期设计可能会被修剪成右边意外的样子。左边和底部边缘被裁剪得太多。
         
当打印多页文件时,印刷车间首先将页面印在一张印张上。然后,这些印张被印刷、折叠和裁切。根据纸张的厚度,每页的实际宽度在内外展开之间可能相差两毫米(0.08″)。因此,要避免将页码等对象放置在离纸张边缘太近的位置,因为与边缘的距离变化对读者来说太明显了。一般来说,可以放置重要内容的安全区域通常距离页面边缘至少5毫米(0.2英寸)。
When printing multi-page documents, the print shop first imposes pages on a large sheet of paper called the signature. Those signatures are then printed, folded, and trimmed. Depending on the thickness of the paper, the real width of each page can differ between the outer and inner spread by two millimetres (0.08″). Therefore, avoid placing objects such as page numbers too close to the edge of the paper because the changing distance from the edge would be too visible for the reader. Generally speaking, the safe area, in which you can place important contents, is usually at least 5 mm (0.2″) from the edge of the page.

将页码放置的太靠近页面边缘可能会导致页码被不适当地裁切。
3. 文字颜色设成RGB色
专业印刷机一般使用青、品、黄、黑(CMYK)四种工艺色以及专色。所有以RGB颜色设置的对象在印前都必须转换成CMYK,不然可能会导致意想不到的偏色。
3. Text colour defined in RGB
Professional printers generally use four process colours — cyan, magenta, yellow, and black (CMYK) —and spot colours. All objects defined in RGB colours have to be converted into CMYK before printing which may lead to an unexpected colour shift.
如果你把黑色的文字设置成RGB色,就不会一次性使用100%的黑色来印刷,而是由四种CMYK色逐一印。四种颜色,四次印刷。很有可能每一次印刷都不会精确地印在前一次上,所以印出来的CMYK文字看起来会略显模糊并偏褐色。因此,标准的黑色文字只能用100%的工艺黑来印,这样才能保持清晰。始终使用印刷(print)或印刷就绪(press-ready)的PDF导出选项,以确保颜色不会被转换为RGB。
If you keep black text in RGB, it won’t be reproduced using 100% black colour in a single pass, but by all four CMYK colours one at a time. Four colors, four passes. The likelihood is that each pass will not print precisely on top of the previous one, so the printed CMYK text will look slightly blurred and brownish. Therefore, standard black text should be printed only by 100% process black so it remains sharp. Always use the print or press-ready PDF export option to make sure colour won’t be converted to RGB.
请注意,一些印刷厂支持PDF/X-4标准[1]和RGB工作流程。在这些情况下,您可以将图像或插图存为RGB。
Please note that some printing houses support PDF/X-4 standard and RGB workflow. In those cases you can keep images or illustrations in RGB.

4. 错误的叠印设置
文档中的每个对象都会叠印其下方的所有元素或将其镂空。除了100%黑色外,所有颜色或图像的默认设置镂空的。
4. Wrong overprint settings
Each object placed into your document will either overprint all elements below itself or knock them out. Knockout is the default setting for every colour or image with the exception of 100% black.
在InDesign中,默认情况下,叠印预览是关闭的,因此您必须在检查文档时将其打开。不幸的是,Publisher目前不提供叠印预览,但有一个简单的变通方法。先导出PDF,然后在Acrobat中打开“叠印预览(Overprint Preview)”进行检查。
In InDesign, the overprint preview is off by default so you’ll have to turn it on when checking your document. Unfortunately, Publisher does not offer overprint preview at the moment, but there’s an easy workaround. Export the PDF first and then check it in Acrobat with Overprint Preview turned on.

屏幕预览可能不是所见即所得,这可能会导致叠印或镂空。始终在打开叠印预览的情况下检查你的文件。

镂空:青色字母不会在黄色背景上叠印,以保持其蓝色。

叠印:将青色字母叠印在黄色背景上,保持其蓝色。在黄色背景上叠印青色字母会导致颜色变为绿色。
5. 被遗忘的专色
如果您在使用 CMYK 工艺印刷的文件中保留专色,它们将被转换为 CMYK 等值色,这可能会导致一个悲伤的意外。例如,金属金的潘通色在纸上可能看起来像一个丑陋的棕色阴影。
5. Forgotten spot colours
If you keep spot colour(s) in a document intended for printing using CMYK process colours, they will be converted into their CMYK equivalent which may lead to a sad surprise. For instance, the metallic gold Pantone colour may look like an ugly shade of brown on the paper.
为了避免意外的结果,在生成印刷就绪的PDF之前,确保文档中没有不需要的专色。专业提示:专色可能是导入的图稿的一部分,所以你可能也需要调整链接的文件。
请注意,一些印刷厂支持PDF/X-4标准和RGB格式的工作流程。在这些情况下,您可以将图像或插图保留为RGB格式。
To avoid unintended results, make sure there are no unwanted spot colours in your document before generating the press-ready PDF. Pro tip: spot colours can be part of imported artwork, so you may need to adjust linked files too.
Please note that some printing houses support PDF/X-4 standard and RGB workflow. In those cases you can keep images or illustrations in RGB.
 
6. 奇怪或错误的页码
有些客户没有意识到宣传册的总页数必须被4整除。对于杂志或书籍,印刷厂可能会要求页码数能被8甚至16整除。如果你收到一个设计14页的文件的要求,你就要意识到无论如何你都要给印刷厂发送一个16页的PDF文件。
6. Odd or wrong number of pages
Some clients do not realize the total number of pages of a brochure must be divisible by four. In the case of magazines or books, the printing press may require page numbers divisible by 8 or even 16. If you get a request to design a 14-page document, just realize you’ll have to send a 16-page PDF to the printer anyway.
始终牢记技术要求,尤其是在早期设计阶段。在最后一刻从一个386页的文档中删除两页,看似没什么大不了的,但可能会很麻烦。

Always keep the technological requirements in mind, especially during the early design stage. Removing two pages from a 386-page document in the very last moment may not seem like big deal, but it can be troublesome.
7. 错误的文档尺寸
始终检查文档尺寸是否与最终页面尺寸相匹配。印刷机使用的拼版软件依赖于“裁剪框”,这是桌面出版应用程序嵌入PDF中的最终页面尺寸的定义。
7. Wrong document dimensions
Always check whether the document dimensions match the finished page size. Imposition software used by printers rely on the “Trim Box”, a definition of the final page size embedded in the PDF by desktop publishing apps.
如果您将一张名片放在一个大的A4或信纸大小的文件中间(即使您包含裁剪标记和出血),拼版软件也无法轻松处理该文件。只向印刷厂发送单个页面,不要发送展板或试图在应用程序中添加页面。印刷厂会自行处理拼版问题。
If you place a business card in the middle of a large A4 or letter-sized document (even if you include crop marks and bleed), the imposition software cannot process the file easily. Send only individual pages to the printer; do not send spreads or try to impose pages in your app. Printing houses will deal with imposition on their own.

左:红线代表正确的裁切框。右:裁切框(红线)与预期的最终文档尺寸不匹配。

8. 字体太小,线太细
每种技术都有其局限性,所以要避免使用极细的线条和极小的字体。虽然胶印机可以完美处理0.1pt的黑色对象,但数字打印机可能无法打印。用彩色或者灰色的色调打印极小的文字或细小的对象可能导致部分或完全无法辨认。如果您没有足够的印制经验,请在下单前将您的设计稿提交给印刷厂检查。
8. Fonts too small, rules too thin
Every technology has its limits, so avoid extremely thin lines and very small font sizes. While offset printers can handle black 0.1 pt rules perfectly, digital printers may fail to print them. Very small texts or thin rules printed in colour or shades of gray can be partially or completely illegible. If you don’t have enough experience with printing, submit your design for approval to the printer before placing your order.

9点字母在使用0.25点线框的100%黑和使用150线的40%黑下印刷的对比。如果同时放大,您可以看到半色调呈现度太低,无法清晰地再现该物象。
         
请注意,由于纸张的吸收性和所使用的印刷技术,油墨在接触纸张时可能会略有扩散。这种被称为“网点扩大(胀墨)”的效应可能会导致印刷黑色背景上的白色字时出现问题,尤其是在胶版纸上印刷时。在这种情况下,很细小的字体可能会直接消失。
Please note that due to the absorption of paper and printing technology used, the ink may slightly spread when it contacts the paper. This effect called “dot gain” can cause problems with thin, white text on a black background, especially when printing on uncoated paper. In this scenario very thin type can simply disappear.
9. 错误的颜色配置文件
如果你设计的广告中带有照片,相同的PDF印刷在铜版纸、胶版纸和新闻纸,不同纸张上照片的呈现会不同。例如,铜版纸有涂层在上面,使油墨留在表面,而不是被吸收。而胶版纸或新闻纸则没有这层,所以墨水会很快被吸收。这种吸收速度会改变颜色的显示、图像的清晰度和其他重要细节。为了尽可能一致地再现色彩,你必须使用三种不同的色彩配置文件(ICC配置文件)将RGB图像转换为CMYK。
9. Wrong colour profile
If you design an ad with a photo in it and have the same PDF printed on coated, uncoated, and newspaper paper, each photo will be reproduced differently. For example, coated paper has a layer on top that makes ink remain on the surface instead of being absorbed. Uncoated or newsprint doesn’t have that layer, so ink gets absorbed quickly. This absorption rate changes how colors appear, the crispness of images, and other important details. To reproduce the colours as consistently as possible, you have to convert RGB images into CMYK using three different colour profiles (ICC profiles).
你可以在位图编辑器中转换照片,但结果是你会有三个不同的图像文件(适用于铜版纸、胶版纸和新闻纸)。在从InDesign或Publisher导出PDF的过程中选择正确的色彩配置文件会更方便。在向印厂发送文件之前,请向他们索取适合您设计的正确配置文件。

You could convert the photo in a bitmap editor, but as a result you will have three different image files (intended for coated, uncoated, and newsprint paper). It is more convenient to select the right colour profile during the PDF export process from InDesign or Publisher. Ask your printer for the correct profile for your job before sending them the files.
不幸的是,首选的色彩配置文件取决于您所居住的地区和印刷厂的先进程度。在最高级别,Adobe忽略了在其Creative Cloud应用程序中包含最新标准欧洲色彩配置文件的要求,因此在与欧洲印刷商和设计师打交道时,您将不得不从欧洲色彩倡议网站(European Color Initiative website)手动安装它们。
Unfortunately, the preferred colour profile depends on the region in which you live and how advanced the printing house is. At the top level, Adobe ignores the requests to include the newest standard European colour profiles in their Creative Cloud apps, so when dealing with European printers and designers, you will have to install them manually from the European Color Initiative website.

吸墨率较高的纸张需要较少的墨水,因此CMYK值取决于使用的纸张类型。ICC配置文件允许就铜版纸、胶版纸、新闻纸和其他材料上使用的油墨总量进行正确的颜色转换。
         
10. 文本框太小
检查您的文档,看看文本框右下角是否有红色的小“加号”或箭头图标。当一个文本框对于它所包含的文本来说太小的时候,这个指示器会显示。它可能只是文本末尾的空行,也可能是你要引用的著名作家的署名。幸运的是,InDesign和Publisher都会在导出此类PDF之前向您发出警告(除非禁用此警告)。
10. Text box too-small
Check your document for the little red “plus” or arrow icon at the bottom right of a text frame. This indicator shows when a text box is too small for the text it contains. It could simply be an empty line at the end of your text or it could be the byline for the famous writer you are quoting. Fortunately, both InDesign and Publisher will warn you before exporting such PDFs (unless this warning is disabled).

InDesign(左)和Publisher(右)中的文本溢出符号。
正如你所看到的,为打印做准备并不神奇,只要遵循一些简单的规则就可以了。现在你已经准备好了,让我们把你的项目送到印刷厂吧!

As you can see, preparing for print isn’t magic, just follow a few simple rules. Now that you’re ready, let’s get your project to the printer!
翻译:朱奎 
审校:刘钊、姜兆勤
Translator:Kui Zhu
Reviewer:Zhao Liu/Kushim Jiang

原文链接:https://mp.weixin.qq.com/s?src=11&timestamp=1653403926&ver=3818&signature=OS3D63u4HWwQ*mNY14deBxfQ1jdG7XmEXKU9yGZTPvmzkjf*ryVkYJpZ7vyoVA4cEtnBGO7LMldjVwPdDqaF9Q2ivY0HL0CwEO3VMlw-n5BdTjIegrsvoGGwkH06n4Z5&new=1

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