How you denoise renderered images in Blender? I am wanting to use Blender as a denoiser as well as a renderer, but I can't find how to bring an image in and denoise it in the compositor. I have tried using the despeckle node but I still can't seem to find the right way to do it.
The Denoising Feature is only available for rendered images as it takes information from the unrendered scene as well as the pixel data of the rendered image to "guess" the right values of each pixel. 

So unfortunately the denoiser isn't available for external images. There are a few compositing solutions available though. Here are some node groups you can use.