Tracing an imported image
Tracing an imported image
The topic of Chapter 13 is Live Trace, and Illustrator's Live Trace feature allows you to automatically convert pixel-based imagery into vector-based artwork. There are a couple of different approaches you might take. You might start with a continuous tone photograph. You can trace digital photographs if you like. That's not the common approach, and that's not an approach we are going to see in this chapter. Rather, we'll take a look at how you can trace Photoshop artwork, like these letters right here, and I'll come back to this illustration in just a moment. Or, how you can start with traditional tools such as pen and paper, go ahead and scan in your artwork, and then develop it inside of Illustrator, as in the case of this artwork right here.
It's called Very large flag.ai. And this illustration, it's huge, by the way. It's 5 feet wide and 3 feet tall so that we could actually output an enormous flag. It's a piece of vector-based artwork, but it started off looking like this. I worked together this initial sketch using a ballpoint pen and a piece of paper, and then I ultimately scanned it into Photoshop. We will see how that entire process worked. Finally, I was able to develop this artwork into this flag art right there. So you can make some amazing progress using this Live Trace feature.
Now, a lot of teachers, very early on when they're teaching Illustrator, they will start off with Live Trace, because it is a highly automated feature and it does create path outlines for you and eliminates a lot of that manual labor associated with the Pen tool and the other tools that we looked at in the Fundamentals portion of this series. The reason I don't start with Live Trace is that it's not applicable to most of the artwork you create inside of Illustrator. For example, I've got this guy open here, Pen tool creature.ai. Remember this is the final piece of artwork that we created back in Chapter 9 in the Fundamentals series.
And there is just no way that you're going to create this artwork using Live Trace. For one thing, we have these incredibly smooth path outlines, so some very precise curves. We also have these uniform strokes, we have these differently colored areas. This is absolutely a piece of Pen tool art. You're not going to get anything like this using the Live Trace feature. However, for a piece of artwork like this where we are trying to simulate real-world tools and we are not interested in creating a lot of different path outlines, that is, we are not trying to distinguish different areas of color using strokes and the like, we just have a few different fill colors going on.
This kind of artwork is absolutely ideally suited to Live Trace. I need to tell you though, even though this is an automated feature, and you'll see how splendidly it works in just a moment, that does not mean it creates automatic artwork. This piece of art that we are looking at right now took me several hours to create. So I don't want you to think that Live Trace creates absolute pieces of art lickety-split, that's not the way it works. Anyways, we will see this one shortly. Let's go back to the letters, for starters here, and the name of this file is Hand-drawn characters.ai and these are a series of brushstrokes that I created inside Photoshop, once again using a Wacom Tablet.
Then I went ahead and placed the image into Illustrator by going up to the File menu and choosing the Place command, or if you loaded dekeKeys, you've got a keyboard shortcut of Ctrl+Alt+D, Cmd+Option+D on the Mac. However, I've already done this in advance inside of this file. So if you go over to the layers panel you'll see a layer called Image. If you twirl it open therein is the linked image which is called Alphabet.psd. I am going to go ahead and meatball it to select it, and then in order to trace these characters, and you may very well wonder, well, why didn't I draw these characters inside of Illustrator in the first place? Why did I create them in Photoshop and now I am going to trace them in Illustrator? For the simple reason that I drew these characters years ago and I'm too lazy to go back in Illustrator and redraw them right now, because that will take an awful lot of time, whereas as you will see, tracing them happens very quickly.
Now I will go out to the Live Trace button, which is now available to me in the Control panel, and I should also show you, by the way, that here in the Control panel you can see not only the name of the linked file, but you can also see its resolution. So in this case the resolution is 72 pixels per inch; a very low resolution file. It's actually a fairly large file though. This illustration measures about 22 inches wide, about 16 inches tall. So we've got a lot of pixels available to us. It's just that the resolution is set quite low. And Illustrator likes this, Illustrator rewards you when you work with low resolution files by not bugging you.
Basically, it gives you very fast results and it doesn't deliver any alert messages. As you'll see you will get a warning if you work with high-resolution art. However, you're going to get better results with high-resolution art as well, but for now we are going to start low. Then I will go over to this Live Trace button and all I have to do is click on it, and bang! Illustrator goes ahead and traces the artwork, and it's done. It's actually converted the image to a Live Trace object, so that I can edit my tracing settings anytime I like. Now I want you to see that by default Illustrator goes ahead and generates a black-and-white tracing.
So we don't have any of the colors we had a moment ago. And, I've lost a line of type. So I will go ahead and Ctrl+Z or Cmd+Z on the Mac, so you can see what I am talking about. That will reinstate my original multicolor image here. You can see that this orange line of type went away as did this yellow background. That's because those colors are closer to white than they are to black. But you can change that. You can force Illustrator to trace those elements. I will press Ctrl+Shift+Z or Cmd+ Shift+Z to redo the tracing and then notice up here inside the Control panel there is this Threshold value and if you hover over it, it says this is the value used to separate black from white.
All pixels lighter are converted to white, all pixels darker are converted to black. Well, a Threshold setting of 128 is medium gray. So 0 is black, 255 is White. This is the world of luminance inside of Photoshop. So if you want to trace lighter colors with black, then you need to increase that Threshold value. I am going to go ahead and set the Threshold to 200 and then press the Enter key or the Return key on the Mac. That goes ahead and traces the orange text without tracing the yellow background behind the numbers.
And we get this nice black-and-white rendering. So that's the simplest way to trace inside of Illustrator. I will show you three more ways to apply the Live Trace feature in the next exercise.
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