Tracing

Tracing

This chapter describes the means and tools of tracing – an interactive procedure that allows extraction of vectors from a raster image, and also to smooth or to delete objects of a monochrome raster image.
Tracing is based on the technology of local recognition of geometrical raster entities. Using this technology, the program identifies raster lines as a line, arc or circle, and generates the appropriate vector objects. Pick raster objects on the image, and the program creates vector objects that approximate the objects chosen.
This method adds power and flexibility to the automatic conversion process. When tracing, it is possible to classify line widths of raster image objects, transform only the necessary ones and transfer the results to separate layers.
Tracing can work on colour or grey-scale, and monochrome images. It is possible to vectorize raster lines, arcs, circles, arbitrary curves (polylines) and also outlines of vector areas.
When processing images; tracing can be used to convert raster objects to vector objects. It can also be used for smoothing, and deleting objects. Depending on the specified tracing mode, the raster object is either deleted, or left intact on the image. Thus, it is possible to transform a raster line to vector object, or only to create a vector copy of a raster line. It is also possible to set a mode in which tracing does not create any replacement vector objects thus deleting them. There is one more mode that automatically replaces a raster line by the rasterized vector object.
On monochrome images lines, arcs, circles, hatches, symbols, and arbitrary curves (raster polylines) and area objects as closed polylines can be traced. On colour and greyscale images all types of objects can be traced, except for hatches and symbols.