No apparently there is no way without WIC.
Within SharpDX Samples there are two example project which illustrate how to encode images.
There is a new(ish) one which "can" leverage the hardware by using a Direct3D11.Device
https://github.com/sharpdx/SharpDX-Samples/tree/master/Desktop/Direct2D1/OfflineImageProcessingApp/Program.cs
And the old one https://github.com/sharpdx/SharpDX-Samples/blob/master/Desktop/Direct2D1/RenderToWicApp/Program.cs using the WicRenderTarget
If you take the code from the first one, you should actually get what you want, still you need Wic to encode the Bitmap to the destination image format (jpg, png...)