A Basic Guide to Vectorizing and Cutting Raster or Bit Image Clip Art
Last week’s article dealt with compound vector clip art files and the problems in cutting them.
This week, we’ll tackle an even more common and vexing problem; the ‘no cuttable object’ error message. This is the uncooperative reply you get from your sign software when you try to plot an image that is not in vector format. What you have is a raster image masquerading as a vector file.
Sending a raster image to a vinyl cutter is like trying to enter a speedboat in a NASCAR race. It’s a non-starter. Before you can cut that image, you have to convert it to a cuttable object. This can take a few seconds or the better part of an hour depending on the complexity of the file. And if you don’t have the right software, you can’t even get started.
Let’s take a look at the problem, the solution, and the process for turning a “no cuttable object” message into a finished decal.
Raster and Vector Image Files
There are two basic kinds of image files used in digital graphics: raster and vector. Raster files are made up of dots or pixels. We generally don’t think of them that way because the dots or pixels are so small, our eyes don’t perceive them. These file formats, also known as “bitmap” or “bit image” files, are commonly used by devices like scanners, digital cameras, and digital printers. (That’s why when you blow up these images on your screen, you see the square dots on the screen. It’s also why when blown up too large, it looks like it has the “jaggies”, you are seeing the individual dots.)
Vector files are composed of simple nodes and arcs, also known as points and paths. Think of a vector file as a “connect the dots” puzzle. The dots are points and the lines you draw from one dot to the other are the paths that define the shape. The paths can of course be straight or curved. As a vinyl cutter plots a file, it is essentially connecting the dots based on the directions from the software.
To summerize, raster file are composed of many small dot, or bits; vector images are composed of arcs, circles, and lines.
Raster files can’t be used with vinyl cutters because your plotter has no way of converting dots or pixels into arcs circles and lines (points and paths). So the file must first be converted to a vector format. This problem occurs often in sign making is because one of the most commonly used file formats for clip art is a raster-vector hybrid. EPS – encapsulated post script- files are so named because they can encapsulate or combine raster and vector data in one image file.
This comes in very handy when you’re designing an image that has to be printed and cut. But if you get an .EPS clip art file with encapsulated raster data, and try to send it to your plotter, you’ll get the dreaded “no cuttable object” message. That means you have a speedboat on a race car track; a non-starter. However, if you have the right software and know how to use it, you can put wheels on it and send it zooming toward the finish line.
Vectorizing Raster (Bit Image) Files
You can convert your raster image to a vector image by converting the pixels into points and paths. This process is called vectorizing or bitmap tracing. This is an essential function for computer aided sign making and is found in LXI EXPERT, Master, and Master Plus. LXi Apprentice is provided for those who want to design in a different application and send finished files to the cutter, so the Auto Trace tool is absent in the entry level package. The same tools are available in FlexiSign, FlexiExpert, and FlexiSign-PRO. If you’re using LXi Apprentice, FlexiStarter or FlexiLetter, you can’t put wheels on your speedboat without a software upgrade.
So how do you trace that EPS file? The process is pretty simple in LXI. Simply click on the image with the Select tool to highlight it, then swap the Select Tool for the Auto Trace or Color Trace tool; the big Z in your toolbar. Then click on the selected bitmap image to start the conversion. The default process places the new vector file on top of the bitmap, so it may look like nothing’s happened. Not to worry. Just move the original file to the side to see the vectorized version.
After tracing or vectorizing, you will probably need to edit the file. Raster files generally contain a lot more raw data than vector files, so the raster to vector conversion may result in an image with too many points. This will cause jagged paths and result in slower cutting as the plotter stops to articulate each of the unnecessary points. The solution is to grab your Path Edit tools, and clean up that artwork.
Clean Up the Initial Vectorized Image
Path Edit tools allow you to change the number of nodes or points on the path and alter the path characteristics between the points. All vector software has them. Mastering path editing is essential to getting the most out of your software, so invest some time and get to know how yours work. In addition to cleaning up vectorized raster files, path editing is a great way to customize fonts to further distinguish your designs.
In LXI Master Plus, the Path Edit toolbar has 23 different tools. With such an extensive tool kit, you can exercise complete control over your vector files. The basic Select Point Tool allows you to finesse the curves that connect the dots. The process of optimizing or cleaning up a traced raster file can take a few seconds or over an hour depending on the complexity of the file. So if someone’s bringing you a raster image that you need to trace and optimize before cutting, charge an extra design fee.
If you can’t get a handle on the process or just don’t have time, you can always outsource it and pay someone else to vectorize the file. But you ought to at least know how to do it in case you have to. To shorten your learning curve, we offer this link to another of our enlightening Tech Support Knowledge Base resources. This one is a step by step tutorial of the entire process of vectorizing a raster file, from start to finish. Click here to view.
The next time you get a “no cuttable object” message, you’ll know how to handle it. Rather than being stuck with a non-starter, just grab your Auto Trace and Path Edit tools, put a set of custom wheels on that speedboat, and get back in the race.