Syncfusion UI controls for UWP provide color picker and color palette controls. This package contains the following controls.
Color palette: https://www.syncfusion.com/uwp-ui-controls/color-palette?utm_source=nuget&utm_medium=listing
ImageGlue is a toolkit for the creation and modification of still images. It can be used in .NET desktop applications or in .NET server pages.
Read and write a host of media formats including: BMP, PNG, TIFF, Fax TIFF, JPEG / JFIF, GIF, Photoshop (PSD), QuickDraw PICT, Targa, QuickTime Image...