HPDFEncodePredictor Function

Encodes complete raster rows with the PDF TIFF or PNG predictor transforms before Flate or LZW compression

Declaration

function HPDFEncodePredictor(const Data: AnsiString; Predictor, Colors,
  BitsPerComponent, Columns: Integer; MaxOutputBytes: Int64= 0): AnsiString;

HPDFPredictor

Name	Purpose
`Data`	Unfiltered rows packed in PDF sample order
`Predictor`	`1` for identity, `2` for TIFF horizontal differencing, `10` to `14` for fixed PNG filters, or `15` for adaptive per-row PNG selection
`Colors`	Number of colour components per pixel
`BitsPerComponent`	Sample width of 1, 2, 4, 8, or 16 bits
`Columns`	Pixel count in each complete input row
`MaxOutputBytes`	Optional hard output ceiling, or zero for no explicit ceiling

Returns predictor-encoded bytes ready for a matching compression filter

The input length must be an exact multiple of the calculated row size
TIFF encoding supports packed and 16-bit samples and preserves unused row padding bits
PNG predictor 15 scores None, Sub, Up, Average, and Paeth for every row and emits the smallest residual score
HPDFTryEncodePredictor returns an error message instead of raising EHPDFPredictorError
Use the same predictor geometry in the stream /DecodeParms dictionary

Predicted := HPDFEncodePredictor(Raster, 15, 3, 8, Width);
Decoded := HPDFDecodePredictor(Predicted, 15, 3, 8, Width);