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Capturing and Optimizing Screenshots for Print

If you’ve ever done design work for any type of software or web-centric company, you have undoubtedly come across the need to capture screenshots for print purposes. This is usually for demonstrative reasons, and it’s a graphic technique employed where just showing the reader a screenshot (usually with a few callouts) can do more than several pages of explanatory text.

The trickier part for designers often comes with saving the images. Since the screen captures are by nature low resolution (72 dpi, screen resolution), converting them for print takes a bit of software trickery.

Getting the Images

For Windows: To capture the whole screen, simply press “Print Screen” (sometimes labeled “Prnt Scrn”). To capture a pixel-perfect version of just the active window, hold “Alt” while pressing “Print Screen.” Both techniques will place an exact image of the screen or window into the Clipboard, and from there, a simple Ctrl-V will paste the graphic into whatever application you wish. Unless circumstances dictate otherwise, Adobe Photoshop is recommended.

For Mac OS9: Apple’s screen capture is a bit different. Shift + Command + 3 will take a snapshot of the desktop as is, and leave “Picture 1.PICT” file in the root directory of the hard drive. Shift + Command + 4 will give you a crosshair to drag around to capture segments; this will also leave a PICT in the hard drive. Caps Lock + Shift + Command + 4 will grab a window, and Shift + Control + Command + 3 will take a shot of the whole screen and have the image ready to paste into an open document instead of copying it to the hard drive.

For Mac OSX: Any of the methods for MacOS work the same in OSX, except that the final image is pasted onto the desktop as a TIFF file. There is also a small utility called Grab in the Utilities Folder that has a few, slightly more advanced functions. For the serious screen capturer, it might be worth investigating.

To Raster or to Vector?

Before proceeding, it is important to decide whether the final screenshot will be in raster (bitmapped) or vector format. While a raster can be scaled upward at a later date, this must be done within Photoshop and the actual file size becomes very large very quickly.

Vector is the opposite; it is a small file that can be easily scaled to infinite sizes directly within the page layout application. However, because of the incredibly complex information inside the images, they can easily choke a computer’s resources after placing only a few. This option is best when there are no more than a few screenshots on a page.

Raster Pro’s: Good for many screenshots on one page; low computer resources.

Raster Con’s: Large file size; fixed dimensions; drastic re-sizing must be done in Photoshop.

Vector Pro’s: Low file size; infinitely scalable; dimensions can be altered right in native page layout program.

Vector Con’s: Hogs computing resources, can present problems come print time.

Preparing a Raster Screenshot

Inside Photoshop, make sure the screenshot is cropped exactly on the edges to avoid awkward bleeds. (For full screen captures, this is not an issue.) Convert the colors to CMYK, which will change the look slightly. (This is especially evident in Mac OSX, where the crisp blue of the Aqua interface gets thinned out in the CMYK conversion; adjusting the level of Cyan just slightly can help combat this problem.) When performing the conversion, flatten the image.

If you’re using OSX or Windows XP in normal mode (ie, not emulating Windows 2000), you’ll notice that the top corners are rounded, and the few pixels that are normally transparent have been filled. After converting to CMYK, double click the Background layer to make it active and give it whatever name you wish. Zoom into the corner, and with the eraser tool set to “Pencil” Mode with a 1-pixel brush at 100% opacity, manually remove those few rogue pixels. You should see the grey and white checkered background underneath the removed blocks.

From there, go to Image > Image Size … and change the resolution to 300 from 72 pixels/inch. Make sure the “Constrain Proportions” box is checked, and select “Nearest Neighbor” from the “Resample Image” dropdown menu. This last part will avoid anti-aliasing, keeping the new high-resolution screenshot a perfect replica of the original capture.

What format the image is saved at depends on your layout program. For InDesign users, simply save the image as a PSD file without flattening the image. This will retain the transparency needed for proper OSX and Windows XP screenshots, and leave the actual image uncompressed.

For QuarkXpress users, either a TIFF or EPS will work, but you must create a clipping path in Photoshop for the rounded corners. To accomplish this, simply hold “Alt” and click on the layer, after you have deleted the extra corner pixels described above. This will give you a “running ants” selection around the screenshot. Open the “Paths” palette, and from the submenu, choose “Make Work Path” and give it a tolerance of one pixel. This will transform the selection to a clipping path. Name the path by double-clicking Work Path. (Note the path must have a name to work correctly.) Import the graphic into Quark and bring up the “Modify” palette either by double-clicking the image, or selecting the image and hitting Ctrl-B. From the “Clipping” tab, choose “Embedded Path” from the dropdown, then the name of your path from the new dropdown that appears. Leave the “Outset” value at 0.

Note that the original distribution of Photoshop 6 had a bug where clipping paths were not exported correctly. Adobe released a fix for this, so please make sure you’re running version 6.01. Later versions of Photoshop do not have this bug.

Preparing a Vector Screenshot

From Photoshop, save the screen grab image as a 24-bit BMP file. This format is completely uncompressed, so there is no risk of degradation as with JPG or GIF. If you’re using OSX or XP, don’t worry about removing the corners as described above—we’ll do that later.

Close Photoshop and open Macromedia Flash (Version 5 or later is recommended). In a new movie, import (Ctrl-R) the BMP you just saved. It will appear on the stage, but do not resize it at all—if you can’t see it, zoom in and out, but don’t resize the image. Doing so will create inconsistencies if you’re using multiple screenshots, and throw off the pixel-perfect conversion you’re about to perform.

Go to Modify > Bitmap > Trace Bitmap. Use the following settings: Color Threshold: 1, Minimum Area: 1, Curve Fit: Pixel, Corner Threshold: Normal. Hit “Okay” and wait. For large screenshots, this can take awhile. Flash is taking every single pixel in the bitmap and converting it to a tiny vector square of color—basically mimicking the raster image with millions of independent shapes. With large fields of color (like a white background in a screenshot of a Windows Explorer window), Flash will merge them into one vector shape, greatly reducing processing time.

Important: Flash’s tracing can take some time. It might seem as though the program has crashed, but it’s just thinking, I promise. I use a 2 GHz Pentium 4 with 2 GB of RAM, and certain screenshots take almost twenty minutes to render. Most take a few seconds.

When the tracing is complete, the image is already selected, so do not click off it. If you do, hit Ctrl-A to select everything again. Choose File > Export > Export Image. Give it a name and save it as an EPS 3.0 (*.eps) file. As a small bonus, this process converts the image to CMYK.

Close Flash and open a vector-editing program like Illustrator. Open the new EPS file.

Update: There is a better, easier way to get the Flash-created files into Illustrator. After Flash is done tracing the image, simply copy the image (Ctrl-C) and paste it (Ctrl-V) directly into a blank CMYK Illustrator document. Not only is this easier, but it eliminates the degredation in the RGB to CMYK color conversion that occurs when Flash saves an EPS—this new method gives you a near-perfect match. (This update brought to my attention by a graphicPUSH reader, whose contact info I have since lost.)

If your screenshots are of the OSX/XP variety, zoom into the top corners and with the Direct Selection Tool (the white arrow in the toolbar, selectable by hitting “A”), select the shape around the window curve and hit delete. Do this for both corners.

Make sure the screenshot sits completely within the Artboard. If not, there is a good chance you will experience some weird cropping issues in the page layout program. This often requires resizing the artboard, which can be done from File > Document Setup. Do not resize the screenshot! Resizing can be done in the page layout program, and since it is now vector, it can be transformed any which way and not lose quality.

Save the image as an Illustrator 9 EPS. I have run into problems using the native AI format (for instance, Quark doesn’t recognize it), and Illustrator 10 EPS’s often do some funky things with InDesign. To ensure minimum problems down the road, Illustrator 9 EPS is the way to go. If you’re using Illustrator CS, save through the Export option, and choose “Illustrator Legacy EPS.”

Very Important Tips

1. When capturing screenshots in Windows XP, make sure Text Effects is turned off. You can check this by going to Start > Settings > Control Panel > Display > Appearance and clicking on the “Effects Button.” The second check mark controls font smoothing, and should be turned off completely when making screenshots. This is absolutely imperative if making vector screenshots, as font smoothing will increase Flash’s processing time exponentially.
2. For vector screenshots, rendering time in Flash is greatly increased with the complexity of the artwork. For instance, gratuitous gradients have brought my machine to a stuttering halt. If the Flash-exported EPS opens up as a text field of gibberish, the screenshot was too complex for Flash’s engine. Consider editing the BMP file in Photoshop, and trying again. Simple is better! Flat fields of color work best.
3. When laying out more than one screenshot in a spread, it is best to keep them all the same size. If one has to be reduced to 50%, they all should be; readers easily spots inconsistencies.
4. Although drop shadows are an often over-used tool in graphic design, they complement screenshots very well. For OSX captures, it is even more critical to maintain the native look with soft shadows.
5. For security, aesthetic, or conceptual reasons, it is often necessary to edit screenshots. This is best done through Photoshop, and there are several tricks to know that will make your life easier. In Windows, the color of the grey bars is not an even hex color; it is actually #E0DFE3. Also, to edit text in a screenshot, use this text setting in Photoshop: 11pt Tahoma with font smoothing off. This is the font for tool bars, etc, and can also be used to replace a URL in a browser shot.
6. When placing complex vector screenshots, place a blank white field behind the image. A printer’s rip can choke on a vector capture since there are microscopic holes between the squares, but the field of white prevents this.

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wrote the following on Sunday March 21, 2010

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