12 Things You May Not Know You Can Do With PDF Files In Mac Preview

Hi this is Gary with MacMost.com. Here are 12 things that you may not know you can do with PDF files in the Mac Preview App.

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So you probably have used Preview to open and view PDF files. But you can do a lot more with PDF files in Preview than just looking at them. This first one may seem obvious to a lot of you but some people don't know this. You can click and fill in PDF forms right in Preview. Now the PDF has to be built in a certain way to allow this. A lot of PDF's are just text on a white background. But some PDF's actually have special elements and fields and you can see here when I move my cursor over these fields they change color. Sometimes you don't see these colors here but you could click in there and you can type to fill out the field. I think one of the reasons people don't know this is because a lot of websites will have a PDF form you can download and it will say you need Adobe Reader to be able to fill this out. But Preview works just fine. Maybe twenty years ago Adobe Reader was the only PDF viewer that did it. But now most PDF viewers allow you to fill out forms. Then you can print or save and the information will be saved in those fields. 

But what if the PDF doesn't have that ability. In this form here I can't click anywhere and enter text. It is just text and other elements on a white background. There are no fields to fill in. But you can still fill it in using Annotations. I can click here on the Annotations tool and I can click on Text and then I could take this text box, fill it in with something, and then I can drag it to where I want. I can also set the Font and Size and all of that. So I can actually put annotations on top of this. If I'm worried about the person on the other end not being able to view annotations all I need to do is simply print and then save it out as a PDF. 

Which is my third tip. Using Print will actually bake in Annotations. So if I Save this out there's a difference here. This file still has Annotations in it and I can change them . But if I close it and open up this one which I Saved the Annotations are baked in. I can select them to copy text. But you can see I can't change them. It's not an element anymore.

Now you may know all about using the Annotations tool to write text and put boxes and arrows and all sorts of things. But you could also just simply highlight text. This is useful if you've got a PDF and you're using it, say, in a class or maybe it's meeting notes at work and you want to highlight something you can select some text and then you can use this highlighter tool here. You simply click it to highlight something or if you want to click here you can actually get different colors. Then you can get these highlights and you can go through the document and highlight elements in it like you are taking notes. You can also see a list of everything you've highlighted by changing the sidebar to the Highlights and Notes sidebar.

Now Notes are something that's also really useful that does use Markup Tools. I can turn on Markup Tools here. Then you can click on the Note button and it creates this little sticky note. You can type some text in it. When you click off of it it shrinks to this little box where you can put anywhere and note that the Notes appear with the Highlights and Notes Sidebar on the left side. So you can highlight and add notes to an entire document that you're using it to study and then go and look at the list here to quickly review all your highlights and notes.

Now you can also Delete pages in a PDF. So I can select a page here in the left sidebar and I can simply hit the delete key and it removes it. So you can see the page is now missing. I can go, maybe to the end here, and get rid of some pages there as well. You can Shift Click to select a range of pages and delete them. You can delete a page in the middle and when you save it you won't have those pages anymore. So if you have a document that say has some instructions and then a form you can get rid of the instructions and just save the form.

You could also rearrange pages. So here in the left sidebar if I wanted to I could click on a page and drag it and change the order of the pages. So if you get something where things are in the wrong order you can switch those pages around here using the left sidebar thumbnails.

You can also merge PDF documents. One way to do that is to open up the first one, then turn on the left sidebar for thumbnails. Then you can just drag and drop other PDF documents into the sidebar here. So I can add this one after that and I could add another one in-between them or I can add it after it here at the bottom. Now you can see I have three pages. If I save and then close this document and reopen it you can see I've got those three pages now in there. It's a three page PDF. So if you've got things in different parts, like maybe you've written something in Pages but you also have created parts of the PDF in a page layout program you can use Preview to combine them into one document.

Now you can Crop PDF documents as well just like you can with an image. So the way to do that is to go into Annotation Tools and select the rectangle here. So you can select an area. Then you can select an area of the PDF. Once it's all selected you can hit the Crop button here. You can do Tools, Crop, Command K. It's going to give you a warning that it's not actually going to delete this area. So you're not going to save any space. It will just make everything invisible. So now you've just got this which is handy if that's all you want to print or all that you want to see the next time you open up the document. 

You can also white out parts of an image. So here you get like a boarding pass and they ask you to print it and you get all these big ads here in full color on the page and you know how much ink that's going to use. So what you can do here is create a box, just make sure the color of the box is white. You don't need a border around it so no border. You can expand the box to cover the spot that you want. Now you know that the ads are underneath this box but when you print, the printer doesn't care. It's not going to use the ink to print that white section.

Now if you want you can password protect a PDF. When it's on your computer, of course, it's protected because you have a password for your account. Nobody can get into your account without your password. But say you're going to want to put this in a public space or share this with somebody and only you and they know the password and you want to have that extra level of protection. So you go to File and then Export, Set to PDF and check Encrypt and then you can enter a password here, verify it, save it and now you see a little lock there over the PDF. If I double click on it it's going to ask me for that password. Most PDF viewers know how to ask for passwords so even if you're sending it to somebody on a different system their PDF is going to ask them for the same password which will decrypt it. It doesn't just lock the file. It actually encrypts it. So really there's no way to get into the file without knowing the password. 

You can also use Preview to convert PDF's to image files which will be useful if you've got something that you want to upload to a site that doesn't accept PDF's. It wants JPEG or something. So in Preview here with the PDF open you can export and you can choose an image format like JPEG or PNG and with JPEG you can even set the resolution. You can also set the compression level. Lower means a smaller file size but less quality. Higher means a larger file size and better quality. 

Now you may already know that you can view PDF's in a variety of ways. You can go to View and do a continuous scroll where you see the pages like this. You can do single page where you're only going to see one page at a time and you can do two pages where you can see facing pages. But there's also Slideshow. You can view PDF pages just like an image slideshow. So you can go to View and then Slideshow, or Shift Command F, and it will show you the pages as a slideshow. You can use the arrow keys on your keyboard to flip through the different pages. 

Preview is a pretty powerful PDF viewer. You can pretty much do anything except create PDF's. That of course you would do in an app that's appropriate for the type of document you want to create. Like maybe using Pages for basic word processing documents and a professional page layout program for more complex documents.