Bitmaps and Their Pre-preparation for Vectorizing

Author: Charles Grage

Published: July 18, 2002

Revised: April 04, 2005

I guess a question that has been asked over and over again and should be answered is “Why should we vectorize our art?”  Simply put, we should vectorize our art for scalability, storage, and platform compatibility.

 You can vectorize an image using many different tools.  You can import an image into both Corel Draw and Adobe Illustrator and vectorize the file one line at a time using the line drawing tools.  You can use the automated vectoring tool in Illustrator to create the vectors.  One can use Corel Trace.  The easiest tool to use Adobe Streamline.  The problem with all of the methods though is that what you get out at the end is dependent on what you put in.  So I advocate a bit of preparatory “cleaning” to the image so it will trace easier no matter what method you choose to use.

 Bitmap formats we should use are *.pcx, *.gif and *.tif within our own computer systems.  Under no circumstances should we use the *.jpg format as it is a lossy format. *.jpgs are called lossy because the compression algorithm used to compress the file during the save procedure loses bits.  Optimally the *.pcx file type should be used as the universal bitmap format for artwork as the *.gif and *.tif file formats come in many different forms and flavors which are not 100% compatible across all software packages.

 Why should we pre-process a bitmap before processing it through one of the tracing programs?  We should pre-process the bitmap image so as to reduce file size and memory usage.  The larger the image in size and the more memory it takes up and makes it a memory hog when it comes time to trace it.  We all combat slow machine syndrome, and while more memory is better, the smaller the file the easier it will be to work with.  Now here is where it will seem a bit confusing, we should also scan images as large as possible to aid in the reduction of error and to simplify the cleaning and touching up of a bitmap prior to vectorizing.

 How do we clean up an image?  You can use Adobe Photo Paint, or Corel Paint or any number of other bitmap editing programs of your choice.  But you will need to remove the background or background color and isolate the image, clean lines that may have merged in the scanning process or fill in lines that where too light to be recognized by the scanning process. You will need to look at the lines and curves of your drawing and smooth out any odd bumps that will get in the way of giving you an accurate trace.  To which I must add that an accurate trace is never really that accurate.  Again, what we are producing with the vector is an illusion.  If the curve is not quite smooth enough after the tracing procedure then you may need to take it into a vector editing program to smooth it out and again clean it up.  You can use Adobe Illustrator, Freehand, Corel Draw, if you used Adobe Streamline to create the vector, before you save the final *.eps you can clean it up but the point/node editing control tools are a bit loose and lack definition.  Again with Streamline (as of version 4) you must edit it within the session.  Once the session is closed you cannot reopen the file and continue editing the image.  You will have to open the file in a vector-editing program as previously discussed. 

Once again to reduce the error of the end vector, using the largest original artwork, one needs to scan as large as they possibly can.  This can take up huge amounts of hard drive space.  Then start the cleaning process remove backgrounds, fix lines and convert the image/file to a B&W *.pcx file.  And then proceed to vectorizing with the method you are most comfortable with.

 Remember carving glass is all the process of creating an illusion.  We use our ability in sculpting and carving glass to fill out the illusion that we define through line, light and shadow.