PDF documents are so common that its actually difficult to imagine any student or professional today not using them extensively. PDF documents fill a special and important niche in the electronic data revolution. To a very large extent they have (thankfully) replaced bulky (and often ridiculously expensive) textbooks.
Now you can have a library of books which weigh nothing and are easy to manage and can be transferred between devices and transmitted easily.
However, to make the most of working with PDF documents there are some important things to know. One of these is a concept called inheritable zoom. This is a feature which, if you are working with a document – especially a larger one like a textbook where you jump around between chapters and pages often – you will easily notice.
One thing that is obviously important about an electronic document is the actual display of the text and its size. This is the zoom level of the document. Most people will have a certain comfortable zoom level which is usually closely related to the electronic display on which the documents are being viewed. For example, on one laptop I use which has a 15.6″ HD+ (1600×900) display, the perfect zoom level seems to be 146%.
So let’s say you have a document and you open it up to work on it on your system. The initial view is too small so you zoom in to a level where the text is large but not too large. You are now happy with it.
But then you go to a bookmark in the document and suddenly the zoom level changes. So you manually set the zoom level back to where you had it. Then later you open another bookmark and jump to another page, only to have the zoom level reset yet again.
This happens when the zoom level is hardcoded into the bookmarks, which is generally a bad idea. A better idea is that the zoom level of bookmarks is inherited, meaning it will stay at whatever the zoom level was set to previously.
This kind of makes logical sense and you would think its obvious, but a surprising number of documents I have worked with do not have inheritable zoom, but rather fixed zoom. The upshot is that you have to keep manually adjusting the zoom level every time you visit a new bookmark (which is annoying).
There is an easy way to fix this, which is the purpose of this post, and I encourage everyone who works with PDF documents on a regular basis to become familiar with it. Here is how:
First you need to get the Open Source tool called JPdfBookmarks (look for the binaries download of the latest version. Download it and unzip it with 7-zip. The run jpdfbookmarks.exe.
From inside JPdfBookmarks open the pdf document that you want to fix. Then under the Tools menu select dump and save the dump file (you can just name it dump.txt or whatever else you want). Now open the dump file in text editor. I highly recommend using Notepad+ – another essential and Open Source app – for a reason that will be apparent in a minute.
Open the dump file in Notepad+ and you will see something like this:
Notice the numbers at the end of each row. Its actually a set of three numbers separated by commas. The last of these numbers is the zoom level. 1.0 means a zoom level of 100%. It is a hardcoded zoom level. Every bookmark that is opened will automatically open at 100% zoom regardless of where you had it set previously. This is not inheritable zoom. It is bad and we don’t want it.
To fix it we need to change 1.0 (or whatever else it might be hardcoded as in your documents) to 0.0. For example, a 130% zoom level would be 1.3. I’ve seen documents where the zoom levels for some bookmarks were values like 0.998 – a close approximation of 100% where the setting must have somehow gotten minced. You will need to look at what the zoom levels are set to at the end of each line, each of which corresponds to a bookmark. Then you will need to do a search and replace so that they all get set to zoom level 0.0.
We can employ the powerful and simple to use search-and-replace tool in Notepad+ to do this. Select Search -> Replace from the menu and you will see the following window:
In the Find what textbox input the hardcoded zoom level of the bookmarks. You will notice that I didn’t just put “1.0” but instead I put “,1.0”. This is to be safe, because the characters “1.0” might occur in some other place in the document that I do not want to change. Even using “,1.0” it is not safe to assume that those characters might not occur somewhere else in the document unrelated to the bookmark zoom level so I always recommend scanning over the document very quickly to make sure.
In the Replace field enter “,0.0”. After scanning the document to verify that “,1.0” (or whatever other zoom level it is that you are replacing) doesn’t occur anywhere else in the text, then select the Replace All button and save the file in Notepad+.
Then go back to the JPdfBookmarks window and select Tools -> Load. Select the dump file that was just saved. Then select File -> Save to save it.
At this point the document has now been partially fixed and the zoom level of all bookmarks is set to inheritable. Now for all of this to make sense a few more things need to be changed. If you’re using Adobe Acrobat then open up the document and go to File -> Properties to open the settings for the document.
Under the Initial View tab look at the settings under Layout and Magnification. When you open the document, do you always want to see the bookmarks in the navigation pane on the left side? (for many textbooks I prefer this, but for book-books I usually don’t) If you do want to see the bookmarks every time, then under Navigation Tab select Bookmarks Panel and Page, otherwise select Page Only.
For the Page Layout setting I recommend Single Page Continuous although you may prefer any of the other settings. Personally I like the documents to scroll similar to the way web pages do, which is what Single Page Continuous is. If you want something more like an e-reader such as Kindle, then select Single Page.
Ok this next setting is the all-important one: Magnification. What is the sweet-spot magnification level on your computer? As I metioned above, on one of my main laptops it is 146%. This then is where to set it.
Now, on another device with a different display and zoom level sweet spot, this can be set to something else. If you want to have the document set to always open at one magnification or the other depending on the system, then it will have to be copied to the other system and a different magnification level will be set there.
If you use a shared document on a network share drive or cloud storage, then obviously you will have to manually change the zoom level when you open the document on the other system or else find a magnification level that you are happy with on both systems.
You could also set the magnification level to Default, Actual Size, Fit Page, Fit Width, Fit Height, or Fit Visible and see how any of these work out for you.
If you are going to be annotating the document then you are probably only going to want to be using one copy, not two different ones. So you can either try to find a common magnification level that works between all your systems or try one of the other settings.
Next in the settings is the Open to page option. I have one document where the cover of the book is the first page and it is an odd size, smaller than the rest of the document. If I have it set to open this cover page as the initial page and have selected the Resize window to initial page option under Window Options its going to be a problem, because the Acrobat window will shrink to the size of the small cover page. Then when I select a bookmark whatever subsequent page is opened will be too large for the window and partially cut off. No good.
So what I do is select a reasonable initial page under Open to page. It could be a second title page that is the same size as other pages, or a table of contents page.
Under Window Options then I would select Resize window to initial page except that if you are going to try playing with something other than a fixed magnification level with a document then you might not want this. If your operating system can remember the size of the window for this document that would be great. However my experience is that Acrobat only remembers the window size of whatever PDF document was open last, not the size of each specific document. At any rate, you can be aware of this and experiment if you like with window size and initial document size. The settings I suggest here are the ones I’ve found to be the least hassle.
Finally, under User Interface Options, you may want to select Hide menu bar and Hide toolbars. If there are only two keyboard shortcuts you remember for Acrobat, those should be F8 and F9. These are the keys to show/hide the Toolbars and the Menu bar. Make sure to save the document after editing the settings.
[The other ultra-important shortcuts to remember are: h – hand tool, v – edit (select) text, spacebar – temporarily toggle hand tool while in text edit, and Ctrl-Shift-n – Go to Page.]
Reference, credit, and thanks to codebyjoshua.blogspot.com: PDF Bookmarks: Change Zoom level and Name of PDF Bookmarks