Use CorelDraw’s Unsharp Mask function (Bitmaps –> Sharpen –> Unsharp Mark) to optimize the engraving results. This tool increases the contrast at the transition point between bright and dark pixels. The details in the image (e.g. hairs, eyelashes, etc.) become clearer.
The percentage defines how much brighter or darker the affected pixels become. The radius decides how many pixels are affected. In most cases, the radius is used. The higher the radius, the more the image looks like a drawing.
Pay attention to the Unsharp Mask on materials that can be engraved easily (for example, anodized aluminum). If the radius is too high, eventually all imperfections are transferred onto the material.
-Josh Stephens, Trotec Laser