All posts by Jeremy Schultz

Tutorial: Eliminating Jaggies

How two of Photoshop’s most basic tools can turn a pixellated scan into a quality bitmap image

I suppose it’s the initiation rite of any newspaper production designer: the sales rep’s client wants their logo scanned in for the next day’s ad, and when you ask for the Illustrator file or PDF they instead hand you a god-awful fax. “Just scan it in,” they say, and you know that no matter what you say or how you explain the real-life problem of working with poor originals, they will only beg you to make it work because it’s easier than going back to the client and asking for a press-ready file that they have long since misplaced.

Did I tell you that the ad’s a full page? “Yeah, sorry, I guess it will have to be blown up some.”

This is when we have to deal with the “jaggies”. I call it “pixellation”; my wife calls it “chunky.” When bitmaps are enlarged, when line art is scanned at a too-low resolution or when you are scanning original line art that has already been converted to a low-resolution bitmap (such as line art that has come across the fax machine), you’ll get the block-by-block construction that makes curves and edges jagged and line art horrendous to look at.

But there is a Photoshop technique I’ve developed in production environments that will often eliminate jaggies or at the least minimize them, and it uses only two basic Photoshop commands that intermediate or even novice users are familiar with.

Moving mountains

Figure 1: The “5 & Diner” logo.

This “5 & Diner” logo (fig.1) was supplied to us by the client, and it’s been scanned in from a slick at a resolution of only 200 pixels per inch. Line art resolution for good reproduction is 800ppi minimum, so this graphic will need some enlargement before we place it in the layout. No problem!

(1) Enlarge image to desired size with resolution of 800ppi or greater (fig.2)

Figure 2: Enlarged logo, complete with jaggies.

In this case we will keep the image size the same but increase resolution from 200ppi to 800ppi. You can convert a bitmap image like this to grayscale mode before enlarging and Photoshop will perform some anti-aliasing on the edges, but for a bitmap with this poor quality, enlarging to a resolution four times greater will still give you a bad case of jaggies. See the comparison (fig.3 and fig.4):

Figure 3: Enlarging in grayscale mode.

Figure 4: Enlarging in bitmap mode.

I’ll take my chances with the bitmap.

The next step, if you haven’t done so already, is to:

(2) Set your image mode to grayscale

You’ll see why in a moment.

The next step will be to obliterate those craggy peaks, and we’ll use one of Photoshop’s most beloved tools to do it, the Gaussian Blur.

(3) Use Gaussian Blur to smooth out the pixellated edges

The key to a good blur is to blur out the details you don’t want, in this case the jagged edges, while maintaining the details you do want, which are the lines, letters and shapes that make up the logo. I usually bring my Gaussian Blur slider all the way to the left (radius 0.1 pixels) and inch it toward the right until I see the jaggies disappear in a blurry haze. If we had stayed in bitmap mode, we would not have had the necessary blurring, just more jaggies.

Figure 5: Gaussian Blur at radius 3.5 pixels.

The “5 & Diner” logo is a tricky one because it has a moderate case of jaggies but also has some fine details like the small letters and the thin white line between the two thick black lines. I don’t want to blur those details into oblivion so I’ll settle for a blur of radius 3.5 pixels (fig.5). To compare the effects of different blurs for you, I’ll show two other examples here: figure 6 has a blur radius of 2 pixels, figure 7 a blur radius of 7 pixels.

Figure 6: Gaussian Blur at radius 2 pixels.

Figure 7: Gaussian Blur at radius 7 pixels.

It’s ironic that we’re trying to achieve a sharp, smooth bitmap image by first making it a blurry mess, but that’s the way it works! Without Gaussian Blur the only way to remove the jagged edges would be to do some major retouching with the brush tool or even the pixel-by-pixel pencil tool, which has to be one of the oldest tools in Photoshop.

Now that we’ve obliterated the jaggies, and any nice clean line art edges we once had, it’s time to bring those clean edges back with one of Photoshop’s most basic commands:

(4) Select Image–> Mode–> Bitmap… and convert to bitmap using the 50% threshold method (fig.8)

Figure 8: The bitmap image after 50% threshold conversion.

The 50% threshold method basically converts every gray pixel below 50% into white and every gray pixel above 50% into black, and the blurred logo becomes a sharp bitmap again, with the edge of the line art falling right where the blur was at 50% gray.

At this point you are done executing the technique, and have hopefully made your pixellated image into one that can pass for a smooth vector graphic. But I want to illustrate how too much blur or not enough can affect your image.

If you blur too little you will still have some pixellation; if you blur too much the logo’s details will become misshapen, including rounded corners and small white space plugging with black. I am going to execute the bitmap conversion in step four to my other two blurred images and see how they are affected.

Figure 9: Bitmap conversion after Gaussian Blur, radius 2 pixels.

Figure 9 (originally fig. 6, blur radius of 2 pixels) still shows some pronounced jaggies, though mostly it has become more wavy than jagged. This is because Gaussian Blur at such a small blur radius smoothed away only the peaks of the jaggies. But with a blur radius of 2 pixels it seems the resulting bitmap has more readable letters, since the counters (those little white spaces inside the letters) don’t plug with black so much.

Figure 10: Bitmap conversion after Gaussian Blur, radius 7 pixels.

Figure 10 (originally fig.7, blur radius of 7 pixels) has lost the shape of its letters: the “F” characters have lost their legs and the counters have been swallowed up. But those jagged edges are almost completely eliminated; all that’s left is a bit of a wave going through the outer circle.

The amount of blur you use is up to you. Some cases will require more than others and sometimes you will have to judge whether elimination of the jaggies or preservation of the logo’s fine details is more important. It depends on the logo, the original you are working with, and the client’s preferences.

Smoothing out rivers

Figure 11: This logo was supplied with far too little data to make usable line art.

Here is one more example that came across my desk recently. This logo (fig.11) was supplied to me by the client, not as a vector EPS graphic or PDF but as a lowly image embedded in a Word document. Bringing it into Photoshop revealed its resolution to be a weak 300ppi and size of only 1.5 inches wide, which meant trouble because the client wanted it to go all the way across their letter-sized flyer.

Figure 12: The logo after enlarging to full-page size.

Enlarging the image to the desired size created some fierce jaggies as I expected (fig.12). I decided that the fluidity of the line was the most vital and so I cleared away the jaggies with a simple Gaussian Blur of radius 15 pixels (fig.13).

Figure 13: After Gaussian Blur, radius 15 pixels.

Converting to bitmap mode using the 50% threshold method created a wonderfully smooth and fluid line graphic (fig.14) with all the resolution and size I needed for the flyer.

Figure 14: The final bitmap image, completely smooth.

A type trivia treat

I’m sure you noticed that while my white line logo turned out smooth, so did my type, to the point where it was illegible. That’s not good. But I didn’t flinch because I knew it would be far easier and better to retype it in my favorite layout application. I’ll give ten points to whoever can tell me what typeface that logo is using. Bonus points for those rabid type-junkies who can calculate the point size and tracking amount!

Margulis Drops Photoshop CS2 In Favor Of CS

Color-correction guru quits using Adobe’s latest version, citing poor Bridge performance.

Dan Margulis, inaugural inductee into the Photoshop Hall of Fame and one of the world’s foremost color-correction experts, recently announced that, “while [Adobe Photoshop] CS2 is a usable program,” beginning August 1 he reverted back to using its predecessor, Photoshop CS, due to poor performance with the new standalone application Adobe Bridge combined with a less-than-phenomenal set of new features for this most recent upgrade.

In Margulis’ semiannual newsletter, sent to more than 1,000 Photoshop and print professionals on August 15, he basically outlined how in his previous newsletter he had cautioned users “in acquiring software that involves the type of software protection (a.k.a. activation) that was introduced for Photoshop CS (Windows only) and now afflicts all Creative Suite apps on both platforms,” as well as recommending those itching to upgrade to monitor reactions to Bridge, hinting that beta versions of Bridge suggested “there might be serious issues with speed and stability in the shipping product.”

“…the most buginfested piece of major software that the industry has seen since Quark 4.0.0.”

Margulis’ reaction to the activation conundrum was mixed, noting that “it seems that at least half the users [of the PC version] are never bothered by [activation].” But he also pointed out that this meant the remainder of users encountered spontaneous deactivations occasionally and in ten percent of cases a frequent activation malfunction that made the application not worth using. As for Mac users, “either nobody is moving from Photoshop CS to CS2 or else the activation is working well, because I am not aware of any complaints.” Score one for Mac addicts.

As for Bridge, well… “the most buginfested piece of major software that the industry has seen since Quark 4.0.0.” Ouch. Margulis cited several glitches and performance issues, including:

  • Slow performance on many operating systems
  • Loss of cache data
  • Frequent crashing
  • Bugs and errors when dragging and dropping image icons, including complete loss of image files

Being a beta-tester for Adobe, Margulis received a free copy of Photoshop CS2, but stated he would not have bought it himself because of stability concerns with Bridge as well as the activation procedure, “because I am so frequently without access to the Internet” that is required to activate. Margulis used CS2 at his home from February until August, at which time he downgraded to CS for all future work. “The performance hit with Bridge is just too severe to be compensated for by the other new features of CS2.” Margulis did add that he would keep CS2 for specific tools, including Camera Raw, the Surface Blur filter and new perspective tools.

Typeradio.org Offers Podcasts For Typography Addicts

Typeradio.org interviews to go in podcast format

typeradio.org

Typeradio.org has been conducting interviews at typography events all over the world for a year or so now, and if you have an iPod you can now download them as podcasts. They tell me that the podcasts will work with any software that supports podcasts, but they designed to work best with iTunes.

Click this link to get signed up!

I’ve downloaded a bunch, including interviews with Peter Saville, Stefan Sagmeister, Erik Speikermann, House Industries and Christian Schwartz among many others. My new iPod (the old one died!) is still in its plastic wrap so I haven’t listened to these yet, but I’ll post some reactions and reflections after I take a listen.

Alien Skin Plug-Ins Now 100% Tiger-Compatible

All Photoshop plug-ins now Tiger-compatible, including Eye Candy 5

Alien Skin Software today announced that their Photoshop plug-ins have been updated to include compatibility with Mac OS X 10.4 (Tiger, released earlier this year) as well fixes to some minor bugs. The updates are free and available to registered Mac and PC users of the following:

  • Eye Candy® 5: Nature
  • Eye Candy® 5: Textures

And these for Macintosh users only:

  • Eye Candy® 4000
  • Xenofex® 2
  • Image Doctor®
  • Splat!®

Click here for more information and to download updates.

If you have any technical issues with updating the plug-ins or other questions, you can contact Alien Skin at 1888-921-SKIN (1-919-832-4124 for customers outside the United States) or e-mail support@alienskin.com.

About: Designorati:Photoshop

D:Photoshop strives to be a well-written source of news, information and techniques for intermediate and advanced users of Photoshop. Users who have a few years of Photoshop experience and a good grasp of its basic tools and tactics will benefit from this ongoing source of production techniques, step-by-step tutorials, reviews of upcoming Photoshop-related products and industry news.

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