I was scaling using the scale boxes in the sprite collection editor. As an extreme test, I was scaling down from 10x. I was NOT using a picture size that was a multiple of 2, I was using a picture size of 240 x 240.
So, I had a sprite of 24 x 24. I scaled it up in Photoshop by a factor of 10 such that every apparent pixel was made of 10 actual pixels. I dropped that into a sprite collection and set the scale boxes to .1 .1 .1. The size is right, but there is kinda a grey shadow around the edge.
As far as filtering, I may not know what that is. I am using point sampled, but not premultiplied alpha.