When applying selective sharpening to a noisy low-light image in post-production, what is the specific benefit over applying a global sharpening adjustment?

When applying sharpening to a noisy low-light image in post-production, the specific benefit of selective sharpening over global sharpening is the ability to enhance desired details without simultaneously exaggerating image noise in other areas. A noisy low-light image is one captured under dim conditions, resulting in random variations in pixel brightness and color, often appearing as grain or speckles, especially in darker or smooth areas. Sharpening is an image processing technique that increases the contrast along edges in an image, making details appear clearer and more defined. Global sharpening applies this edge contrast enhancement uniformly across the entire image. The drawback of global sharpening on a noisy low-light image is that it treats the fine, random variations of noise as if they were legitimate edges, thereby amplifying the noise and making it much more prominent and distracting throughout the image, especially in smooth or out-of-focus areas where noise is most visible. Selective sharpening, in contrast, allows the user to apply sharpening only to specific parts of the image or based on certain characteristics, such as areas with strong, defined edges, while intentionally avoiding or reducing the effect in areas prone to noise. This is typically achieved through techniques like masking, where a user draws or defines an area to apply the effect, or through algorithmic edge detection, where the software identifies and sharpens only the most significant edges, ignoring the subtle, random 'edges' found in noise. For example, a photographer might selectively sharpen the eyes and texture of a subject's clothing while protecting the smooth skin and out-of-focus background from sharpening to prevent noise amplification. This targeted approach ensures that the visual impact of the photograph is improved by enhancing critical details, while simultaneously preserving image quality by preventing the undesirable magnification of noise in areas where it would be most noticeable, resulting in a cleaner and more professional-looking final image.