Sometimes clients ask us if we have any recommendations for the PDFs that they use to make flipbooks. While basically, anything goes, there are a few things that could be useful for you to know if you design the PDF yourself, or want to pass some guidelines to the person who designs it for you.
- Should I use a specific PDF format or version?
- What quality should I use for my images/how many PPI?
- Any tips for text?
- What font size should I use?
- Can I use different-sized pages?
- What about crop marks?
Should I use a specific PDF format or version?
Almost all PDFs import perfectly fine, you don't have to use a specific format. The only exception is XFA. This format is used for PDFs that are enriched with forms that you can fill out. Adobe itself says that “In many ways, the XFA PDF file format is closer to an HTML file than it is to a traditional PDF file.“ If you have Adobe Acrobat Pro, then you can distill the PDF to turn it back into an ordinary PDF, which you can import without any problem. You’ll lose the forms though.
When it comes to the PDF version (a.k.a. Acrobat compatibility level) we’d recommend avoiding PDF 1.3 (Acrobat 4.0). Overlapping images may get 'sliced up' in this PDF version. If you inspect the PDF very carefully, you will also notice tiny white lines.
During the conversion to a FlippingBook, the effect gets more pronounced. To correct this, try to generate the PDF again in the software where you designed it, and then export it in at least PDF 1.4 (Acrobat 5.0) format. Please note that just saving a 1.3 PDF in 1.4 format won't help - what is already broken won't get fixed this way.
What quality should I use for my images/how many PPI?
There is no need to use more than 225 PPI. Flipbooks are intended for on-screen presentations. If you use larger images, we resize them anyway. Don't worry, they still look great! We just remove unnecessary details that are not visible anyway. This ensures that your pages load quickly. In fact, we advise you not to use very detailed images (1200 PPI or more). The resizing may make them even look worse!
Any tips for text?
- When it comes to text, make sure that the text in the PDF is real text (i.e. it has a font, color, and font size and that you can copy/paste it from the PDF into another document). Sometimes we see that our clients' PDFs consist of images only and even the text is part of the image. If you use real text then it...
- will be converted to an SVG image. That means that it scales very well and looks crisp and clear at all zoom levels.
- can be searched for. By your reader when they use the search option in the flipbook. But also by search engines if you enable this option, so people searching for text in your flipbooks can find it in Google, Bing, and other search engines
- can be selected by your readers and copy/pasted from your flipbooks.
- Use a decent font size. With two pages visible at the same time in a browser, your pages often appear smaller on-screen than in hardcopy versions. Therefore, to keep text readable, make sure that you use a decent font size.
- Avoid 'hidden text'. It is much better to delete invisible text completely than to hide it behind other objects, put it in hidden layers, or make it the same color. Hidden text sometimes prevents us from generating the SVG image for the other text. While your normal text will still be visible, it may be a bit less crispy. You can check for hidden text in Acrobat Acrobat: Tools > Protection > Remove hidden information > Hidden text. Don't enable the other 'hidden information' options like 'Deleted or cropped content' and certainly not 'overlapping objects'.
- Don't use vertical text. If you really need to, then just use several elements of horizontal texts under each other.
- Try to avoid transparent text.
What font size should I use?
We suggest using decent-sized fonts to increase readability. What is decent? That depends mostly on the page size, and to some extent on the font itself.
- If your pages are A5/Half Letter-sized then we recommend 12-point fonts (or 10-point fonts as a minimum). Your text will be readable on pretty much all screens without zooming for most readers.
- If your pages are A4/Letter-sized then we recommend not going much lower than 14-point fonts. This avoids that users with smaller screens, especially mobile devices, will have to zoom a lot.
Note! Not all fonts have the same size at 12 points. Individual fonts can be smaller or bigger. The numbers above apply to standard fonts like Arial, Helvetica, Times New Roman, Verdana, etc.
Can I use different-sized pages?
We don’t recommend different-sized pages, even though it won’t cause any technical errors. You can read more about it in our article that describes how we exactly handle different sized pages. One of the characteristics of our flipbooks is that all pages have the same size. So if you use different sizes, we will add extra white space around your pages to compensate. That looks a bit strange.
What about crop marks?
Sometimes you can see small lines in the corners of your flipbook looking something like this:
These lines (crop marks) show where the paper should be cut after printing by professional printers. We don't remove such crop marks, so make sure to remove them from your PDF before you upload it. You can crop your PDF with Adobe Acrobat. You can also use free online tools like Sejda or PDF Resizer.