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发表于 2024-3-9 22:00:43
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File size and image quality
文件大小和图像质量
Images are a major factor when it comes to PDF file size: the more images there are in a document the larger the file size will be and the higher the quality of those images the larger the file size will be. For print-ready PDF artwork, image quality must match print quality (normally 300 dots per inch) so file size will always be larger than web-ready PDFs which only have to match screen quality (typically 72 to c. 160 pixels per inch).
图像是影响 PDF 文件大小的一个主要因素：文档中的图像越多，文件大小就会越大，而这些图像的质量越高，文件大小就会越大。对于可打印的 PDF 图稿，图像质量必须与打印质量相匹配（通常为每英寸 300 点），因此文件大小始终大于可用于 Web 的 PDF，后者只需与屏幕质量相匹配（通常为每英寸 72 到约 160 像素） 。
While there’s no leeway with print-ready PDFs, there is some with web-ready PDFs. Savings can be made if imagery isn’t that important but if imagery is important, say in a product brochure, file size will need to be higher. It’s a trade-off that needs to be considered. Thankfully, with higher broadband speeds, improvements in email file size caps and larger mobile data allowances, file size has become less important than it used to be.
虽然打印就绪的 PDF 没有余地，但也有一些可用于网络的 PDF。如果图像不是那么重要，则可以节省费用，但如果图像很重要（例如在产品手册中），则文件大小将需要更大。这是一个需要考虑的权衡。值得庆幸的是，随着宽带速度的提高、电子邮件文件大小上限的改进以及移动数据限额的增加，文件大小已经变得不像以前那么重要了。
Colour format
颜色格式
Another difference between web- and print-ready PDFs is colour format: screens use three colours (Red, Green and Blue (RGB)) while print typically uses four (Cyan, Magenta, Yellow and Black (CMYK)), the additional information adding to file size. Colours won’t look the same on screen and in print in a lot of cases so to get the best results and to maintain consistency it’s preferable to stick to the right colour format for the medium.
Web 和打印就绪 PDF 之间的另一个区别是颜色格式：屏幕使用三种颜色（红色、绿色和蓝色 (RGB)），而打印通常使用四种颜色（青色、品红色、黄色和黑色 (CMYK)），附加信息添加到文件大小。在很多情况下，颜色在屏幕上和打印中看起来并不相同，因此为了获得最佳结果并保持一致性，最好坚持使用适合介质的正确颜色格式。
Print suitability
打印适宜性
Web-ready PDFs are suitable only for office or home inkjet or laser printers. They can’t be used for commercial print because neither the quality nor the colour format is correct. Your designer will need to provide you with print-ready PDF artwork prepared to the printer’s or publication’s specifications.
网络就绪 PDF 仅适用于办公室或家庭喷墨或激光打印机。它们不能用于商业印刷，因为质量和颜色格式都不正确。您的设计师需要为您提供符合印刷商或出版物规格的可打印 PDF 图稿。
As for using print-ready PDFs for office or home inkjet or laser printing, they will most likely be larger than the original page size and have printers marks (see below). Some software may not be able to print the document minus the extra page area and marks.
至于使用可打印的 PDF 进行办公室或家庭喷墨或激光打印，它们很可能会大于原始页面尺寸并带有打印机标记（见下文）。某些软件可能无法打印减去额外页面区域和标记的文档。
Font embedding
字体嵌入
Fonts play an important part in graphic design and will have been chosen carefully by your designer to enhance the design. Although it’s not strictly necessary to embed fonts in a web-ready PDF (they’ll be substituted by available local system fonts), if there has been any thought put into design at all then they should be embedded. If design isn’t important and file size is a real issue, not embedding fonts will decrease file size – it’s a bit hit and miss though as some setups may not have suitable substitute fonts available and this may cause layout issues.
字体在图形设计中发挥着重要作用，设计师会仔细选择字体来增强设计。虽然在可用于 Web 的 PDF 中嵌入字体并不是绝对必要的（它们将被可用的本地系统字体替代），但如果在设计中有任何想法，那么就应该嵌入它们。如果设计并不重要并且文件大小是一个真正的问题，那么不嵌入字体会减小文件大小 - 这有点碰运气，因为某些设置可能没有合适的替代字体可用，这可能会导致布局问题。
Transparency
透明度
Transparency can be used by designers to create an effect such as overlaying colour onto part of an image or overlapping two colours to simulate a third. These effects will work in web-ready PDFs but for print purposes transparency needs to be ‘flattened’: the overlaying colour needs to be combined with that segment of the image and a third colour needs to be created for the area where the two colours overlap.
设计人员可以使用透明度来创建效果，例如将颜色叠加到图像的一部分上或重叠两种颜色以模拟第三种颜色。这些效果适用于网络就绪的 PDF，但出于打印目的，透明度需要“展平”：叠加颜色需要与图像的该部分组合，并且需要为两种颜色重叠的区域创建第三种颜色。
Printer’s marks and bleed
印刷痕迹和出血
When, say, a brochure is printed commercially, it’s printed on sheets of paper larger than the finished size. These are then folded, combined in order, bound (e.g., stapled) and trimmed down to the correct final size. The extra paper that ends up on the printer’s floor will have the document’s name and page number detailed and printer’s marks – guides which allow the printer to align each colour accurately as it’s printed and which show where the pages should be folded and trimmed.
例如，当商业印刷小册子时，它印刷在比最终尺寸更大的纸张上。然后将它们折叠、按顺序组合、装订（例如装订）并修剪至正确的最终尺寸。最终落在打印机地板上的额外纸张将包含详细的文档名称和页码以及打印机标记——这些标记允许打印机在打印时准确对齐每种颜色，并显示页面应折叠和修剪的位置。
These marks are added by the designer to the PDF artwork they prepare for the printer or publication. Bleed will also be added, an extra three millimetres on each side where colour or images extend outside where the page is to be trimmed, just as leeway in case there are any slight errors or issues in folding or trimming. The printer or publication will specify which printer’s marks are to appear and how much bleed is to be added. In some instances, they may specify no printers marks or bleed, e.g., when they are slotting an advert into other content on a page.
这些标记由设计者添加到他们为打印机或出版物准备的 PDF 图稿中。还将添加出血，即颜色或图像延伸到要修剪的页面之外的每侧额外三毫米，就像在折叠或修剪时出现任何轻微错误或问题时留有余地。印刷商或出版物将指定要显示哪个印刷标记以及要添加多少出血量。在某些情况下，他们可能会指定没有打印机标记或出血，例如，当他们将广告插入页面上的其他内容时。
So, if you ever come across a PDF on a company’s website which has marks and symbols on the outer edges, you’re most likely looking at print-ready PDF artwork that the website’s owners/maintainers have mistakenly used instead of a web-ready version or have chosen to use rather than request a web-ready version or have the print-ready file converted into the correct format. It happens far more often that you’d think.
因此，如果您在公司网站上发现 PDF 的外缘有标记和符号，那么您很可能看到的是网站所有者/维护者错误使用的可打印 PDF 插图，而不是可用于 Web 的 PDF 插图。版本或已选择使用而不是请求网络就绪版本或将打印就绪文件转换为正确的格式。这种情况发生的频率比你想象的要高得多。
Optimisation and InDesign presets
优化和 InDesign 预设
Tweaking file size, image quality and colour format are some of the ways you can optimise PDFs. Adobe InDesign, the industry-standard page layout application for graphic designers, has presets built in to help automate that optimisation. For PDFs destined for the web, ‘Smallest File Size’ is a good option but you can create a custom preset of your own if, for example, you prefer better image quality. For PDF print artwork, one of the most-used industry-standards is ‘PDF/X-1a:2001’ but your printer may specify another.
调整文件大小、图像质量和颜色格式是优化 PDF 的一些方法。 Adobe InDesign 是面向图形设计师的行业标准页面布局应用程序，它内置了预设来帮助自动化优化。对于发送到网络的 PDF，“最小文件大小”是一个不错的选择，但如果您喜欢更好的图像质量，您也可以创建自己的自定义预设。对于 PDF 打印图稿，最常用的行业标准之一是“PDF/X-1a:2001”，但您的打印机可能会指定另一个标准。
Interactivity
互动性
There is limited scope for adding interactivity to PDFs but you can enrich a reader’s experience by adding links to other pages in the PDF, links to web pages or navigation buttons. Adding links to a table of contents is an easy way to improve a reader’s experience and this can be automated in InDesign when you export a PDF. Interactivity has no function in print-ready PDF artwork.
向 PDF 添加交互性的范围有限，但您可以通过添加 PDF 中其他页面的链接、网页链接或导航按钮来丰富读者的体验。添加到目录的链接是改善读者体验的简单方法，并且在导出 PDF 时可以在 InDesign 中自动执行此操作。交互性对于可打印的 PDF 图稿没有任何作用。
Sharing and sharing format
分享及分享格式
If you want to share a PDF to a certain person or group of people, email is the most convenient method as PDF file sizes are generally low. However, print-ready PDF artwork is normally much larger so a file transfer service such as WeTransfer (free if you’re sending files up to 2 GB) may be needed.
如果您想与某个人或一群人共享 PDF，电子邮件是最方便的方法，因为 PDF 文件大小通常较小。然而，可打印的 PDF 图稿通常要大得多，因此可能需要 WeTransfer 等文件传输服务（如果您发送的文件大小高达 2 GB，则免费）。
Sharing a web-ready PDF as is (.pdf format) is normally fine (unless it’s a very large file) but print-ready PDF artwork should be compressed (.zip format) before sending to protect the file from possible corruption as it passes from server to server.
按原样共享可用于 Web 的 PDF（.pdf 格式）通常没问题（除非它是一个非常大的文件），但可打印的 PDF 图稿应在发送之前进行压缩（.zip 格式），以防止文件在传输过程中可能发生损坏从服务器到服务器。
It’s a good idea to name print-ready PDF artwork so it can be identified easily. You can do this by adding a prefix or suffix to the file name – I always add an ‘X1a-‘ prefix.
最好为可打印的 PDF 图稿命名，以便轻松识别。您可以通过在文件名中添加前缀或后缀来完成此操作 - 我总是添加“X1a-”前缀。
Security
安全
Finally, let’s talk about security. For print-ready PDF artwork, you’ll (presumably) be sending the file to a trusted printer or publication and be using a trusted file transfer method so you shouldn’t need to add security unless the content is sensitive. For web-ready PDFs, you may want only certain people to have access to the file or may want to protect the PDF’s content. In those cases, you can either add a password so only those in the know can open the file or add a password to prevent content being copied and/or printed or limit printing to low quality. You may even want to add passwords to restrict both opening and copying/printing. Just be aware though that PDF security is pretty easily broken if you know how to do it.
最后，我们来谈谈安全性。对于可打印的 PDF 图稿，您（可能）将文件发送到受信任的打印机或出版物，并使用受信任的文件传输方法，因此除非内容敏感，否则您不需要添加安全性。对于可用于网络的 PDF，您可能只希望某些人有权访问该文件，或者可能希望保护 PDF 的内容。在这些情况下，您可以添加密码，以便只有知情者才能打开文件，或者添加密码以防止内容被复制和/或打印或限制打印质量较低。您甚至可能需要添加密码来限制打开和复制/打印。请注意，如果您知道如何做到这一点，PDF 安全性很容易被破坏。
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