Scan2CAD raster to vector conversion software

REVIEW:

Contex SD4490 large format scanner

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Scanning in Black and White

Scanning in black and white is what most CAD users will do most of the time.

Nextimage has two options for scanning in black and white - Fixed Threshold and Adaptive Threshold.

When you select Fixed Threshold, you are given three settings that you can edit using a slider bar: Threshold, Despeckle and Holefill. The Threshold setting is a simple threshold, i.e. parts of an image darker than the threshold value are set to black (foreground), and parts of the image lighter than the threshold value are set to white (background). The Fixed Threshold option is for scanning clean drawings with good foreground / background differentiation.

When you select Adaptive Threshold, you are also given three settings that you can edit: Brightness, Despeckle and Holefill. The Brightness setting is an adaptive threshold, i.e. the threshold is automatically altered in response to the drawing's local foreground / background darkness. The Adaptive Threshold option is for scanning drawings with poor foreground / background differentiation, i.e. dirty, faded, stained or folded ones.

Our dirty test drawing, below, has faint dashes (top left) and a dirty crease (right).

The aim is to scan the drawing so that the faint dashes are found and the dirty crease is lost. This should be possible using an adaptive threshold, however using Nextimage's adaptive thresholding we were unable to achieve the desired result:

Compare this to the same image scanned using the Graphtec CSX300. (Graphtec call their adaptive thresholding "intensity correction".)

While our tests do not mean that Nextimage's adaptive thresholding is less effective at cleaning all dirty drawings, we found it was less effective at cleaning up our dirty test drawing than other scanning software we have tested.

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