【译】Adobe数字出版套件(DPS)中PDF与JPG/PNG图像格式的不同

原文地址：Differences Between PDF and JPG/PNG Image Format for DPS

当PDF图像格式在DPS文章中第一次可用的时候，该格式还有很多限制。最重要的限制是，基于PDF的文章不支持交互操作。因此大多数设计师仍坚持使用JPG/PNG图像格式，除非他们希望用户会在页面上收缩和放大图像。

v18版本的工具改变了这种情况。现在，PDF文章中所有的交互操作与JPG/PNG文章一样好。

在新iPad的视网膜显示屏上，PDF图像格式是被推荐的选择。PDF文章比JPG/PNG文章更小，矢量格式能增强缩放体验。然而，你依然应该了解PDF和JPG/PNG图像格式之间的不同。

PDF的优势

• PDF文章通常比JPG/PNG文章更小，尤其是对于长文章来说；
• PDF文章的页面支持手势缩放；
• PDF格式现在支持所有的交互操作；
• 文件格式小和支持矢量文本的特点，让PDF格式成为新iPad的视网膜显示屏的理想格式；

PDF的劣势

• 只有iOS查看器支持PDF图像格式。无法在桌面查看器或者Andorid设备上观看PDF文章；
• PDF图像格式不支持平滑卷动。如果你导入了多篇文章到Folio中，且设定默认的图像设置为PDF，平滑卷动的文章将转换成JPG或者PNG；
• PDF文章在翻页的时候需要一点点载入时间；
• 在Folio Producer Editor中无法预览PDF文章的缩略图。如果你知道这个限制就没什么问题。不过大多数人在Folio Producer Editor界面中看不到PDF页时，可能会认为页面丢失了。

原文内容：

Differences Between PDF and JPG/PNG Image Format for DPS

When the PDF image format was first made available for DPS articles, the format was limited. Most importantly, interactive overlays were not supported in PDF-based articles, so most designers stuck with the JPG/PNG image format unless they wanted users to be able to pinch & zoom on a page.

With the v18 release of the tools, that changed. Now, all interactive overlays in PDF articles work just as well as they do in JPG/PNG articles.

With the new retina display iPad, using the PDF format has now become the recommended choice for image format. PDF articles are smaller than JPG/PNG articles, and vector content is maintained, resulting in improved scaling. However, there are still some differences between the PDF and JPG/PNG image formats that you should be aware of.

Advantages of PDF

• PDF articles are usually much smaller than JPG/PNG articles, especially long articles.
• Pages in PDF articles can have pinch and zoom enabled.
• All interactive overlays are now supported in PDF.
• The combination of small file size and vector text makes PDF the ideal format for the new retina display iPad.

Disadvantages of PDF

• Only iOS viewers support the PDF image format. You cannot preview PDF articles in the Desktop Viewer or in Android devices.
• Smooth Scrolling articles cannot use the PDF image format. If you import multiple articles into a folio in which the default image setting is PDF, the Smooth Scrolling articles are converted to JPG or PNG.
• There is sometimes a brief load time when flipping to a PDF article.
• In the Folio Producer Editor, preview thumbnails are not available for PDF articles. This shouldn’t be a problem as long as you’re aware of this limitation, but some people look at their PDF folios in the Folio Producer Editor and think their content is missing.