Another image for the Ghastly Gallery!
The sender of this image was particularly interested in converting the text.
Some raster to vector converters have a capability for converting raster text to vector text using Optical Character Recognition (OCR). When you convert raster text using OCR, the vector text is proper editable text rather than a series of uneditable lines and arcs. However, OCR only recognizes raster text where certain conditions are met.
The most important condition - which this image fails - is that the text is easily legible to a human being. Can you read the text in the portion of the image shown below?
Essentially, the image has been scanned at too low a resolution.
As with our previous ghastly image, it is worth remembering that not only is this scan utterly useless for raster to vector conversion, it is utterly useless as an archive scan as well. The information that the original drawing contained has been irretrievably lost.
Again, I'm going to stress the importance of careful scanning by knowledgable operators. Careless scanning, or scanning by operators who don't know what constitutes a good scan or how to produce one, leads to utterly useless scans.
For more information on how to produce useful scans, see Creating high quality scans for raster to vector conversion.