I searched the forum for a similar post and found this: http://developer.nokia.com/community...t=customfilter but it doesn't help in answering my question. When I call RenderAsync() when using my CustomFilter, a NullReferenceException is thrown, which I need to catch and keep calling RenderAsync() until it finally works. Any ideas why? My code is really simple:

using (var source = new BufferImageSource(imgToProcess.data.AsBuffer()))
using (var effect = new FilterEffect(new MyCustomFilter(source)))
using (var renderer = new JpegRenderer(effect))
    IBuffer buf = await renderer.RenderAsync();
for my custom filter, I just overrwrote OnProcess() and that's it. I have a try-catch statement in there, but the exception does not happen there. Any ideas? If I use a new FilterEffect(source) everything works just fine. It seems to be an issue with CustomFilter itself? Thank you for any help!