<PackageReference Include="System.Drawing.Common" Version="10.0.0-preview.1.25080.3" />

ShadowCurveEffect

Increases or decreases the value of a color channel if that channel already has a value that is below half intensity.
using Windows.Win32.Graphics.GdiPlus; namespace System.Drawing.Imaging.Effects { public class ShadowCurveEffect : ColorCurveEffect { public int Shadow => base.AdjustValue; public ShadowCurveEffect(CurveChannel channel, int shadow) : base(CurveAdjustments.AdjustShadow, channel, shadow) { } } }