Vector tracing vs auto-tracing
Manual vector tracing vs auto-tracing
Let me start by saying that if you're a major printing company with a warehouse-sized production department, you probably have nothing to gain by reading this article since you most likely have a diverse art department that handles the problems mentioned here. However, if you're a small business with limited printing experience, or if you just like reading articles, then read on.
Having worked at a couple of small-town screens printing shops - one of which I served as a graphic artist, and both as a full-time screen printer - I know that in the world of printing, time is always of the essence. While the old adage, "time is money" may be no more true than that of the printing realm, this is not an excuse to rush through the early stages of a job - particularly the art development and preparation phase.
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| Manual Vector Tracing |
As many of you may have already discovered, the slightest mistake or omission in the art department can be catastrophic once the job hits the production floor, especially in terms of time efficiency. If a design is not prepared correctly the first time around, both time and money will be wasted because the art department must now adjust the artwork and make the corrections, new separations must be printed, new screens exposed, etc. Virtually an eternity where - had the art been prepared correctly - the job would be halfway finished.
My point is, the art phase of any job should never be taken lightly. Many a time have I seen where an order was placed weeks in advance, and the art department sat on the order until the last minute, where a design was then quickly slapped together out of generic clip art, separations quickly printed and screens exposed. The result is a very generic, cartoonish, "garage shop" look to the design. Now obviously, your customer isn't going to know the difference between a generic design and a genuinely original design, but like any other product in the business world, even the untrained eye can tell roughly how much time was put into something. To you, it's just another print job, but to your customer, who seldom - if ever - deals with printed apparel - the order is the coolest thing ever.
Each customer that walks through your door is no stranger to tee shirt artwork. They see it everywhere they go, from the guy in front of them at a high school football game to the kids standing in line at American Eagle. As they walk through the door, they have in their head a vision of a cool looking tee shirt. These customers may have with them a printout or simplified sketch of what they want their design to look like. It is then the responsibility of the art department to take this seed and turn it into something that will wow the customer. Sometimes, these seeds come in the form of images sent via email, and since your customer knows as much about image resolution as you and I know about deep water crab fishing, they aren't going to know that you can only use an image that is 300 dpi or more, preferably in vector form.
This brings me to another point - don't waste your time trying to explain to your customer WHAT vector art is, because anytime you utter terms like "CMYK," "Pantone," or "anchor point," it's going to go right over their heads and only serve to confuse them more.
At this point, art development is chiefly the responsibility of the artist, who is trained and experienced to deal with this kind of problem.
The two most commonly used vector programs - Corel Draw and Adobe Illustrator - both have an auto-tracing tool that allows any bitmap, jpg, gif, png or any kind of raster image to be "traced" by the computer and thus converted into a vector image.
The problem with these automated tools is that they only work as good as the original image is, so if a customer brings you a low-resolution image, these tools are useless.
Auto-tracing tools work by following what they see as straight lines. I don't mean literally lines, but consider how a pixel looks at extreme close magnification. Zoom in close enough on any bitmap, and you will cease seeing what the image is and see a variety of colored blocks. Each of these blocks is one pixel. Auto tracing tools compare the color values of pixels with adjacent pixels, and if they are relatively the same color, it will interpret that as a "solid color." Where there is a dramatic change in pixel hue, such as where a black outline borders a white background (there would be a couple of grey-shaded pixels between solid black and solid white due to anti-aliasing), the auto-trace would interpret this border as a "line." The problem is that even though it understands that the perimeter of this dramatic hue change is a border of an object, it cannot produce a single, curved line. It instead creates hundreds of individual anchor points, with straight lines between each.
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| Vector trace |
Unless you're printing an image of an 8-bit Mario, this pattern is very undesirable. The only way around this problem is to manually trace an image, either by hand using a light table and tracing paper, or directly using the vector programs "Pen tool" to plot and manipulate your own vector points. This is almost always a painstaking, time-consuming process.
One alternative is to allow the auto-trace to do its thing, then come back behind it deleting unwanted or unnecessary anchor points. This, of course, is also painstaking and time-consuming. The difference is, the time it takes you to "clean up" the image is in addition to the time it took you to fine-tune auto trace, assuming you got worthwhile results at all. Depending on the complexity of the image, you probably would spend as much time deleting and adjusting anchor points generated by an auto trace as you would manually plotting the points yourself.
The bottom line is, auto trace is a neat feature to have, but as I said, it's only as good as the image you're trying to trace. You, the artist, can more easily interpret a raster image - made up of millions of pixels - and translate that image into a collection of various vector shapes.
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