ArcScan requires that you choose a target raster layer prior to using the ArcScan tools and commands. The target raster layer is used for raster selections, raster cleanup, and vectorization.
All rasters that have been symbolized to display unique colors are available in the raster layer list. If your map contains one raster layer, it is set as the target raster layer by default.
- Click the ArcScan Raster Layer drop-down arrow on the ArcScan toolbar.
- Click the target raster layer.