When you start ArtCAM Pro you are in the Assistant's Getting Started page. Click on the Create New Model icon. that will display the Size For New Model dialog box. In the lower left corner of the dialog box you will find a ruler icon with the word "Units" above it. Two small circular choice buttons allow you to pick the measurement system.
The default for ArtCAM, since it was created in England, is metrics or mm. Move your mouse pointer over the inches button and left click it. A small black dot will appear in the button showing the American system has been selected. Before you click on the OK Radio Button be sure to re-dimension your model to the correct amount of inches. Then click the OK Radio Button.
At this point you should be able to start the Face Wizard and import your image. You can not go back and re-dimension the image once it has been imported. ArtCam Pro does not support re-dimensioning--a shortcoming of the software.
Hope this helps you.