Minor Description
According to the PDF spec "LZW and Flate Predictor Functions", both can have post processing with predictors. It is implemented for Flate but not for LZW. I am adding this by using the existing code from the Flate filter, which I will be moving into a helper class.
While looking at the Flate filter, I noticed that its footprint is higher than needed, i.e. there is too much buffering. I will test this separately and commit only if I can measure an improvement.