Lesson 7-4. Tracing color raster images

Brief description: During this lesson you will learn how to trace polylines and contours on color scanned images.

For detailed information on these subject see chapters Tuning tracing, Tracing Modes and Commands, How to trace, Tracing Polylines, Tracing Outlines in the Tracing section of the Quick Start guide.

Tracing raster polylines on color images

Let’s study tracing polylines using the example of Image_1 of the Trace_color.cws file from the Lesson_7 folder.

Choose Open from the File menu. Open the Trace_color.cws file from the Lesson_7 folder.

Before tracing a polyline you need to tune the tracing parameters.
Choose Conversion Options from the Convert menu.

For detailed information on tuning the tracing parameters see section Tracing polylines of Lesson 7-2.

However there are some differences when tracing color images:

Max.Width should be measured exactly on the color boundary of a raster polyline and background. Specify this parameter value slightly greater than the measured width (i.e. if the result of your measurement is equal to 0.24 - enter 0.4 in the Max.Width field).

In the Separate tab, enter 0.2 in the Width field, select checkboxes against the Width and Use Table fields.

Open the Color Accuracy toolbar. Set sensitivity to maximum by moving the slider to the right. Press the Adaptive Raster Erasing button to replace deleted lines with the background color.

INFORMATION: If you set the Adaptive Raster Erasing mode, when tracing in Erasing Mode, the deleted raster data is replaced with the averaged background color.

Open the Raster To Vector toolbar. Choose a tracing mode - for example, Make Vector and Erase Raster by pressing the Make Vector and Erase Raster button and the tracing command - Line Following. Tracing polylines on a color image is the same as tracing polylines on a monochrome image. For detailed information on tracing polylines see section Tracing polylines of Lesson 7-2.

Tracing raster contours on color images

Let’s study how to trace raster contours using Image_2 of the Trace_color.cws file from the Lesson_7 folder.

There are two methods of executing this command, which depend on the Export single contour checkbox in the Trace tab of the Conversion options dialog.

Method 1 - Creating only an outer contour
(the Export single contour checkbox is on)

Choose Conversion Options from the Convert menu. Open the Trace tab. Select the Export single contour checkbox - the program will only create the outer contour.

Open the Inspector by choosing Inspector from the Tools menu. From the Hatch Type field list, choose Solid Fill and in the Color field choose a color.
Open the Raster To Vector toolbar. Choose a tracing mode - Make Vector and Keep Raster by pressing the Make Vector and Keep Raster button and the tracing command - Trace Outline.
Specify a point inside the raster contour.

Specify a point inside contour	The result of tracing contour

Method 2 - Creating both inner and outer contours
(the Export single contour checkbox is off)

• Delete the text from the image:
• Open the Color Accuracy toolbar. (To do this, from the View menu choose Show Toolbar, and then - Color Accuracy).

Set sensitivity to maximum by moving the slider to the right. Press the Adaptive Raster Erasing button to replace deleted lines with the background color.

Select the text using the Inside Window button, which is located on the Select toolbar. Press Delete.

Choose Conversion Options from the Convert menu. Open the Trace tab. Clear the Export single contour checkbox - the program will create inner contours along with the outer contour.

Choose a tracing mode - Make Vector and Keep Raster and the tracing command - Trace Outline. Specify a point inside the raster contour.

Image before tracing	Result of tracing contour

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