HotPDF Docs
Home Contents Overview

JPEG2000 Image Format Support

Overview

HotPDF provides comprehensive support for JPEG2000 image formats, including JP2 and J2K files JPEG2000 is a wavelet-based image compression standard that provides superior compression efficiency and quality compared to traditional JPEG format

Supported Formats

  • JP2: JPEG2000 Part 1 format with complete file structure
  • J2K: JPEG2000 codestream format (raw compressed data)

Key Features

  • Automatic format detection and appropriate processing
  • Support for both lossless and lossy compression
  • Multi-component image support (RGB, RGBA, Grayscale)
  • Advanced bit-depth support (8, 12, 16 bits per component)
  • Direct validated codestream-tile decoding with tile-grid metadata
  • Combined source-region and power-of-two resolution-of-interest decoding
  • Decoded-output budgets for hostile or unexpectedly large codestreams
  • Automatic renderer resolution selection from visible target pixels
  • Bounded parallel reconstruction of independent intersecting tiles
  • Deterministic composition, cancellation, worker-limit, and peak-memory telemetry

Usage Example


// Delphi example - Adding JPEG2000 image to PDF
procedure AddJPEG2000Image;
var
  PDF: THotPDF;
  ImageIndex: Integer;
begin
  PDF := THotPDF.Create(nil);
  try
    PDF.FileName := 'output.pdf';
    PDF.BeginDoc;
    PDF.AddPage;

    // Add a JPEG2000 image - the .jp2 source is decoded and then embedded
    // with the requested compression
    ImageIndex := PDF.AddImage('sample.jp2', icFlate);
    PDF.CurrentPage.ShowImage(ImageIndex, 100, 100, 200, 150, 0);

    // J2K codestream format is also supported
    ImageIndex := PDF.AddImage('sample.j2k', icFlate);
    PDF.CurrentPage.ShowImage(ImageIndex, 100, 300, 200, 150, 0);

    PDF.EndDoc;
  finally
    PDF.Free;
  end;
end;

Technical Implementation

The JPEG2000 support is implemented through the HPDFJpeg2000.pas unit, which provides:

  • THPDFJpeg2000Decoder: Main decoder class for processing JPEG2000 images
  • Format Detection: Automatic identification of JP2, J2K, and JPT formats
  • Header Inspection: InspectHeaderFromByteArray reads dimensions, components and SourceColorSpace without decoding pixel samples
  • Stream Processing: Support for both file and stream-based image loading
  • Tile Access: LoadTileFromByteArray decodes one validated tile and reports its source offset and grid
  • Resolution Selection: LoadRegionFromByteArray combines a source rectangle with a wavelet reduction factor
  • Parallel Tile Decode: LoadRegionFromByteArrayParallel uses independent decoder instances and deterministic row-major composition
  • Loaded PDFs: DecodeLoadedImageRegionAtResolution selects a level that does not under-resolve either target dimension
  • Operation Controls: JPEG2000ParallelTileDecoding and JPEG2000TileWorkerLimit control renderer integration, while GetLastJPEG2000ParallelDecodeStats reports scheduling and budget estimates
  • OpenJPEG Integration: Native linked decoding on Win32 and Win64

Performance Benefits

  • Better compression ratios than traditional JPEG
  • No blocking artifacts at high compression rates
  • Progressive transmission and viewing
  • Region of interest (ROI) encoding support
  • Concurrent reconstruction when a visible region crosses independent codestream tiles
  • Lossless compression option

Compatibility

JPEG2000 support is available in both 32-bit and 64-bit versions of HotPDF and is compatible with all supported Delphi and C++ Builder versions

See Also