| PredictorAlgorithm | Implements different PNG predictor algorithms that is used in PDF files. | code | html |
| Average | We can use raw on the right hand side of the decoding formula because it is already decoded. | code | html |
| None | The none algorithm. | code | html |
| Optimum | In an Uptimum encoded image, each line takes up width*bpp+1 bytes. | code | html |
| Paeth | From http://www.w3.org/TR/PNG-Filters.html: The Paeth filter computes a simple linear function of the three neighboring pixels (left, above, upper left), then chooses as predictor the neighboring pixel closest to the computed value. | code | html |
| Sub | The sub algorithm. | code | html |
| Up | The up algorithm. | code | html |