Your sharpening can also be based on various color ranges you select. All three of the sharpening approaches are based on what the program refers to as Structure (s), Local Contrast (lc) and Focus(f). Structure controls and enhances along fine lines, edges and texture. Local Contrast controls the contrast on the fine lines and edges. Focus applies to areas that are out of focus and either increases or decreases the focus in those areas depending on how you set it. When working on your photos the main screen allows three views, fit to screen, 100% or 300%. The smaller window works as a loupe.