THPDFImageRecompressionCostOptions Record

Tunes the visual-cost image recompression search: quality range and step, perceptual error budget, visual and byte-cost weights, minimum savings and sampling stride

Declaration

THPDFImageRecompressionCostOptions= record
  MinimumQuality: Integer;
  MaximumQuality: Integer;
  QualityStep: Integer;
  MaximumPerceptualError: Double;
  VisualErrorWeight: Double;
  ByteCostWeight: Double;
  MinimumSavingsBytes: Int64;
  SampleStride: Integer;
  class function Default: THPDFImageRecompressionCostOptions; static;
end;

Unit

HPDFDoc

Fields

Field	Purpose
`MinimumQuality`	Lower bound of the swept quality range; by default `30`
`MaximumQuality`	Upper bound of the swept quality range; by default `90`
`QualityStep`	Increment between trial qualities; by default `10`
`MaximumPerceptualError`	Perceptual error a candidate must not exceed to be accepted; by default `3.0`
`VisualErrorWeight`	Weight of the perceptual-error term in the cost score; by default `1.0`
`ByteCostWeight`	Weight of the byte-cost term in the cost score; by default `1.0`
`MinimumSavingsBytes`	Minimum byte saving required before a recompression is kept; by default `1`
`SampleStride`	Pixel stride used when sampling decoded images for the error measurement; by default `4`
`Default`	Class function handing back the values listed above

Usage notes

Start from THPDFImageRecompressionCostOptions.Default and adjust single fields; a larger QualityStep trades accuracy against fewer encoding trials
Raise ByteCostWeight to push the search towards smaller files, or VisualErrorWeight to favour fidelity
Pass the record to THotPDF.OptimizeLoadedImagesByVisualCost and read the matching THPDFImageRecompressionCostInfo for the full outcome accounting

THPDFImageRecompressionCostOptions Record

Declaration

Unit

Fields

Usage notes

Related APIs