Vectorization 3:
Image Extraction and B&W Threshold

Extract Raster Images

Using this function, raster images can be extracted to your hard drive. Print2CAD summarizes all raster images from the PDF to a common image at a 300 dpi resolution.

• Parameter: Extract raster images and save them on your hard drive
  The raster images are extracted and iserted into the converted DWG as elements -Image.

• Parameter: Place the Raster Image in a Background of a Vectorized Drawing
  The raster images are extracted and inserted into the converted DWG as image elements, with the selected transparency and in light or dark gray. This is a very convenient method to check the quality of the Raster 2 Vector and to test the vectorization with various methods and parameters.

• Parameter: Save raster files in the source or destination directory
  The raster images are stored in the target directory.

• Parameter: Save raster files in the following path
  The raster images are stored in the chosen directory.

Vectorization Parameter: Threshold for Black & White

The threshold is a very important factor with which scanned drawings can be cleaned up. It is also a crucial factor for the success or failure of a vectorization.

The vectorization is always carried out based on a Black / White raster image. Based on the threshold value, the program decides what is black and what is white.

For black/white vectorizations, the threshold value for the color black associates the color black to all pixels that are darker than the threshold. The remaining pixels are white.

• If the threshold is too low, important parts of the drawing may disappear.
• If the threshold is too high, parts of the drawing may melt together and will not be identifiable.

Sample: Thresholding of a pixel area (in square the pixel gray color) with a Threshold = 100

Threshold for Color Vectorization

The threshold for colored vectorizations must be split into a separate value for black and a separate value for white. Between the two values, the colors are unchanged.