Preview is OS X’s graphics viewer, fax viewer, scanning
program, and PDF reader. It’s always been teeming with features that
most Mac owners never even knew were there—but now it’s a flagship OS
X program, offering all of Apple’s pet cutting-edge features like Auto
Save, Versions, and full-screen mode. In fact, in Mountain Lion,
Preview also gains the ability to save files online, in your iCloud
locker. And its Share icon (
) lets you send an document to somebody else by
email, AirDrop, or Messages, or send an open graphic via Facebook,
Twitter, or Flickr.
Tip
Preview can even open Microsoft Office documents (Word, PowerPoint, Excel) and iWork documents (Pages, Numbers, Keynote). You can’t edit them in Preview, but you can read them, search them, and print them. No longer must you pay homage to Microsoft’s bottom line just to have a look at the documents people send you.
Preview can import pictures directly from a digital camera (or iPhone), meaning that there are now three OS X apps that can perform that duty. (iPhoto and Image Capture are the other two.) It’s sometimes handy to use Preview for this purpose, though, because it has some great tools for photos: color-correction controls, size/resolution options, format conversion, and so on.
The actual importing process, though, is exactly like using Image Capture. Connect your camera, choose File→Import from [your camera’s name], and carry on as described on Managing Game Center.
Preview can also operate a scanner, auto-straighten the scanned images, and export them as PDF files, JPEG graphics, and so on.
This, too, is exactly like using Image Capture to operate your scanner. Only the first step is different. Open Preview, choose File→Import from Scanner→[your scanner’s name], and proceed as described on Scanners.
Clearly, Apple saved some time by reusing some code.
One hallmark of Preview is its effortless handling of multiples: multiple fax pages, multiple PDF files, batches of photos, and so on. The key to understanding the possibilities is mastering the Sidebar, shown in Figure 16-20. The idea is that these thumbnails let you navigate pages or graphics without having to open a rat’s nest of individual windows.
Figure 16-20. The Sidebar can display thumbnails, a table of contents, or annotations, or it can appear as a full-screen array of thumbnail images. Drag the central scroll bar to make the Sidebar bigger; drag the lower-right corner of the Sidebar to make the whole Preview window bigger.
Tip
You can drag these thumbnails from one Preview window’s Sidebar into another. That’s a great way to mix and match pages from different PDF documents into a single new one, for example.
To hide or show the Sidebar, chose one of these three commands from the View menu:
Thumbnails. This standard view (Figure 16-20, left) offers a scrolling vertical list of miniature pages or photos. Click one to see it at full size in the main window. Make the thumbnails larger or smaller by dragging the window/Sidebar dividing line.
Highlights & Notes. Preview, in Mountain Lion, is a better PDF editor than ever. If you add comments and highlighting to a PDF document, as described later in this section, you can view all of them in this tidy list—and click one to jump to it.
Table of Contents. If you’re looking over photos, this option turns the Sidebar into a scrolling list of their names. If you’ve opened a group of PDFs all at once, you see a list of them. Or, if you have a PDF that contains chapter headings, you see them listed in the Sidebar as, yes, a table of contents.
Contact Sheet. When you choose this view, the main window scrolls away, leaving you with a full screen of thumbnail miniatures. It’s like a light table where you can look over all the photos or PDF pages at once. Make them bigger or smaller using the slider in the lower left.
POWER USERS’ CLINIC: Scaling and Resampling
When you’re fooling around with a picture’s size and resolution in the Change Size dialog box, you might find that a couple of the options take a little explaining.
If “Scale proportionally” is turned on, Preview changes the Height number when you change the Width number, and vice versa. In other words, it won’t let you change the shape of the photo; that’s why a little padlock icon appears to bracket the Height and Width boxes.
If “Resample image” is turned off, then Preview adjusts the image’s size by making the existing dots bigger or smaller—but never changes the number of dots. (That’s why a padlock bracket links all three boxes together. For example, you can make the image larger—but you’ll lower the number of dots per inch.)
If “Resample image” is turned on, then you’re giving Preview permission to add or subtract pixels as necessary to scale the photo up or down. Of course, it can’t create detail that wasn’t there in the original, but if you’re scaling the picture up, it does a decent job of generating new pixels by averaging the colors of the neighboring ones.
Preview is surprisingly versatile. It can display and manipulate pictures saved in a wide variety of formats, including common graphics formats like JPEG, TIFF, PICT, and GIF; less commonly used formats like BMP, PNG, SGI, and TGA; and even Photoshop, EPS, and PDF graphics.
Tip
Don’t miss the Tools→Show Magnifier command. It gives you a loupe: a magnifying circle (or, in a PDF document, a magnifying rectangle) that lets you inspect part of your graphic or PDF file more closely.
If you highlight a group of image files in the Finder and open them all at once (for example, by pressing ⌘-O), Preview opens the first one but lists the thumbnails of the whole group in the Sidebar. You can walk through them with the ↑ and ↓ keys, or you can choose View→Slideshow (Shift-⌘-F) to open a full-screen slideshow.
To crop graphics in Preview, drag across the part of the graphic that you want to keep. To redraw, drag the round handles on the dotted rectangle; or, to proceed with the crop, choose Tools→Crop. (The keyboard shortcut is ⌘-K.)
Since Preview is an Auto Save program, you can always return to the original if you change your mind someday.
Preview is no Photoshop, but it’s getting closer every year. Let us count the ways:
Choose Tools→Show Inspector. A floating palette appears. Click the first tab to see the photo’s name, when it was taken, its pixel dimensions, and so on. Click the second one for even more geeky photo details, including camera settings like the lens type, ISO setting, focus mode, whether the flash was on, and so on. The third tab lets you add keywords, so you’ll be able to search for this image later using Spotlight. (The fourth is for PDF documents only, not photos; it lets you add annotations. A fifth tab appears only in PDF documents—for rotating, cropping, and resizing the file.)
Choose Tools→Adjust Color. A translucent, floating color-adjustment palette appears, teeming with sliders for brightness, contrast, exposure, saturation (color intensity), temperature and tint (color cast), sharpness, and more. See Figure 16-21.
Figure 16-21. Humble little Preview has grown up into a big, strong mini-Photoshop. You can really fix up a photo if you know what you’re doing, using these sliders. Or you can just click the Auto Levels button. It sets all those sliders for you, which generally does an amazing job of making almost any photo look better.
Choose Tools→Adjust Size. This command lets you adjust a photo’s resolution, which comes in handy a lot. For example, you can scale an unwieldy 10-megapixel, gazillion-by-gazillion-pixel shot down to a nice 640 X 480 JPEG that’s small enough to send by email. Or you can shrink a photo down so it fits within a desktop window, for use as a window background.
There’s not much to it. Type in the new print dimensions you want for the photo, in inches or whatever units you choose from the pop-up menu. If you like, you can also change the resolution (the number of pixels per inch) by editing the Resolution box.
Preview doesn’t just open all these file formats—it can also convert among most of them. You can pop open some old Mac PICT files and turn them into BMP files for a Windows user, pry open a TIFF file from a scanner and turn it into a JPEG for use on your Web site, and so on.
All you have to do is open the file you want to convert and choose File→Export. In the box that appears, choose the new format for the image using the Format pop-up menu (JPEG, TIFF, PNG, or Photoshop, for example). Finally, click Save to export the file.
Preview is a nearly full-blown equivalent of Adobe Reader, the free program used by millions to read PDF documents. It lets you search PDF documents, copy text out of them, add comments, fill in forms, click live hyperlinks, add highlighting, circle certain passages, type in notes—features that used to be available only in Adobe’s Acrobat Reader. And now, in the Mountain Lion version, you can even fill out PDF forms, typing into imaginary boxes on the electronic document.
Tip
Don’t forget that Preview is one of OS X’s certified
full-screen apps. That is, you can make it fill your screen,
border to border, by clicking the 
icon in the upper-right corner, as
described on Full-Screen Apps, Mission Control.
You can also flip through the pages of a PDF using the “next page”
gesture: a two-finger swipe on the trackpad.
Here are the basics:
Zoom in and out using ⌘-plus and ⌘-minus.
Use the View menu commands to control how the PDF document appears: as two-page spreads; as single scrolling sheets of “paper towel”; with borders that indicate ends of pages; and so on.
Press the space bar to page through a document (add Shift to page upward. The Page Up and Page Down keys do the same thing.)
Tip
Some PDF documents include a table of contents, which you’ll see in Preview’s Sidebar, complete with flippy triangles that denote chapter headings (Figure 16-20). Use the ↑ and ↓ keys to walk through these chapter headings, and then expand one that looks good by pressing the → key. Collapse it again with the ← key.
In other words, you expand and collapse flippy triangles in Preview just as you do in a Finder list view. (The View→Sidebar submenu also includes Expand All and Collapse All commands.)
Bookmark your place by choosing Bookmarks→Add Bookmark (⌘-D); type a clever name. In future, you’ll be able to return to that spot by choosing its name from the Bookmarks menu.
These remain living, editable entities even after the document is saved and reopened. These are full-blown Acrobat annotations; they’ll show up when your PDF document is opened by Acrobat Reader or even on Windows PCs.
Turn smoothing on or off to improve readability. To find the on/off switch, choose Preview→Preferences, and click the PDF tab. Turn on “Smooth line art and text.” (Though antialiased text generally looks great, it’s sometimes easier to read very small type with antialiasing turned off. It’s a little jagged, but clearer nonetheless.)
To find a word or phrase somewhere in a PDF document, press ⌘-F (or choose Edit→Find→Find) to open the Find box—or just type into the
box at the top of the Sidebar, if it’s
open. Proceed as shown in Figure 16-22.Figure 16-22. Type into the search box. Matches appear in the Sidebar, with page numbers; click one to go there. You can sort the found list either by rank (how likely Preview thinks it is to be what you’re looking for) or in page order; click the appropriate phrase about the list to sort.
The search results show a snippet of the actual text surrounding each “find,” along with the number of matches per page, and even a thumbnail of the page itself. It’s all about context, baby.
If you want to copy material out of a PDF document—for pasting into a word processor, for example, where you can edit it—click the Text tool (the letter A on the toolbar) or choose Tools→Text Tool. Now you can drag through some text (and even graphics) and then choose Edit→Copy, just as though the PDF document were a Web page. You can even drag across page boundaries.
You can save a single page from a PDF as a TIFF file to use it in other graphics, word processing, or page layout programs that might not directly recognize PDF.
To extract a page, use the usual File→Export command, making sure to choose the new file format from the pop-up menu. (If you choose a format like Photoshop or JPEG, Preview converts only the currently selected page of your PDF document. That’s because there’s no such thing as a multipage Photoshop or JPEG graphic. But you already knew that.)
Add keywords to a graphic or PDF (choose Tools→Show Inspector, click the
tab, click the 
button). Later, you’ll be able to call up
these documents with a quick Spotlight search for those
details.
You can type notes (in a box or a bubble), add clickable links (to Web addresses or other spots in the document), or use circles, arrows, rectangles, strikethrough, underlining, or colored highlighting to draw your PDF readers’ attention to certain sections. (You can dress up photos this way, too.) The trick is to open the Edit toolbar, as shown in Figure 16-23.
Figure 16-23. To make the annotation tools appear, click the main toolbar button indicated here by the cursor. Click the button you want, and then drag diagonally to define a rectangle, oval, arrow, link, speech bubble, or thought bubble. Look over the master list of notes using the Tools→Show Inspector.
Once you’ve made an annotation, you can drag it around, drag its control dots to change its shape, edit the text inside it, and so on.
Later, you can view a tidy list of all such annotations by choosing View→Highlighting and Notes.
Of OS X’s 47,000 features, very few are quite as slick or useful as the PDF signature option. It lets your Mac take a picture of your actual written signature, which Preview then stores so that you can slap it into the PDF documents that will come through your life.
The first step is to teach Preview what your signature looks
like. To do that, sign your name on a piece of plain white paper,
using black ink. On the Edit toolbar, click the Signature pop-up
menu, 
, and choose Create Signature from Built-in Camera. (You’ll see your actual camera
name, like iSight Camera or FaceTime HD Camera. And if you don’t see
the Edit toolbar, which is shown in Figure 16-22, choose
View→Show Edit Toolbar.) Now proceed as shown in Figure 16-24.
Figure 16-24. Hold up your written signature page in front of your Mac’s camera. Make sure it’s big enough to fill the box on the left side—never mind that it appears backward—and position it so that it sits on the blue line, as shown here. After a moment, your isolated, beautifully photographed signature appears in the Preview box.
When the positioning looks good, click Accept. You’ve just stored your signature. (You have to do this only once—per signature, anyway.)
When the time comes to sign a document, make the Edit
toolbar visible. From the pop-up menu, choose the signature’s name.
(Preview can store more than one signature; that’s why
this step is necessary.)
Now just click the document where you want the signature to appear. If there’s a line you’re supposed to sign on (such as a “Sign here” line), Preview is smart enough to shrink your scanned signature so that it fits on the line. Nice, huh?
You can delete signatures (and add new ones), if you like,
using the Manage Signatures dialog box. Choose Manage Signatures
from the pop-up menu on the Edit toolbar.
Here’s a new Mountain Lion feature that could save a lot of trees: fill-innable PDF forms.
Lots and lots of PDF documents are forms that you’re supposed to fill out—from IRS tax forms to school permission slips. Preview is smart enough to recognize boxes to fill in, lines to type on, and checkboxes to click, meaning that you don’t have to print, fill out, and then scan these things anymore. And it manages to find those lines, text boxes, and checkboxes on any PDF document, not just those that were originally designed to be filled in by PDF form-filling software. See Figure 16-25.
Figure 16-25. When you fill in a form, the cursor changes automatically into an insertion point when it detects a box or a line that you can fill in. And it turns into a pointing-finger icon when it’s over a checkbox, as shown here. Click to put an X in that box; click again to remove the X. It’s hours of fun for the whole family! When you’re finished, save the document as you would any other. Amazingly, you’ll be able to edit your responses when you open the PDF document again later.