We receive a fair number of scanned images - a lot of them are artwork that has been printed and need to be re-vectorized. There are several characteristic traits for these images:
- Shape edges are often blurry, with the edge transition happening over several pixels.
- The color separation in the printing process leads to colors that do not perfectly overlap. This often causes the pixels around the edges to have "false colors". For example, the lower side of an edge may be a little more cyan, while the upper side is a little more yellow (many combinations are possible).
The key to successful results with scanned artwork is to limit the colors Vector Magic uses by picking the custom colors option in the wizard and to use the right resolution when scanning. You normally want to use the artwork with blending option, as the scanner almost always produces a result with blended edges. The main exception is if you've forced the scanner to just black-and-white, which we don't recommend. Grayscale is usually a better option if you want to get rid of the colors.
Scans usually have some salt-and-pepper noise in addition to being blurry, and the colors can vary quite a bit. You therefore want to use the option of limiting the colors used ("custom colors" option), to minimize the impact of this. It also helps limit the effect of any remaining blurriness.
You want the resolution used when scanning to be such that the edge transitions happen over roughly one pixel. This makes for a sharp image that normally has all the essential information present in the original. If you don't know where to start, try scanning at 150 DPI and go up or down from there depending on how wide your edges are.
You can also scan at a higher resolution (e.g. 300 DPI) and then scale down the image in a bitmap editor. Be sure to use cubic interpolation when doing so to preserve the integrity of the image.
Using these simple techniques usually yields nice results from scanned artwork.
