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CoreJ2K Encoder Parameters — Cheat Sheet

This cheat sheet lists encoder parameter names (exact strings used by ParameterList), short synopsis, and defaults where available. The encoder recognizes the same option names used historically in JJ2000/CSJ2K; use them exactly as keys in a ParameterList.

Usage example (C#):

var p = new ParameterList();
p["rate"] = "0.5";           // set target bitrate (bpp)
byte[] j2k = J2kImage.ToBytes(bitmap, p);

General encoder options (encoder_pinfo)

  • debug — on|off — Print debugging messages. Default: off.
  • disable_jp2_extension — on|off — Disable automatic .jp2 extension when file_format is used. Default: off.
  • file_format — on|off — Wrap codestream in JP2 file format. Default: on.
  • pph_tile — on|off — Pack packet headers into tile headers. Default: off.
  • pph_main — on|off — Pack packet headers into main header. Default: off.
  • pfile — — Load arguments from file. Default: null.
  • tile_parts — — Packets per tile-part. Default: 0.
  • tiles — — Nominal tile dimensions. Default: 0 0 (no tiling).
  • ref — — Image origin in canvas system. Default: 0 0.
  • tref — — Tile partition origin. Default: 0 0.
  • rate — — Output bitrate in bits-per-pixel; -1 means lossless/no discard. Default: -1.
  • lossless — on|off — Turn on lossless compression (reversible quantization + w5x3). Default: off.
  • i — <image file(s)> — Input image(s) (PGM/PPM/PGX). Mandatory for low-level flow.
  • o — — Output filename (mandatory for CLI encoding). For library use, ToBytes returns bytes.
  • verbose — on|off — Print encoding info. Default: on.
  • v — on|off — Print version/copyright. Default: off.
  • u — on|off — Print usage. Default: off.

Tiling and packet options

  • tiles — "W H" — Nominal tile width and height, e.g. "1024 1024".
  • tile_parts — integer — Max packets per tile-part (0 = all in first tile-part).
  • pph_tile, pph_main — on|off — Packed packet headers (tile/main).
  • Psop, Peph — on|off — Use Psop/Peph markers (packet header / end-of-packet header).

Wavelet transform options (prefix W)

Source: ForwardWT.ParameterInfo

  • Wlev — — Number of wavelet decomposition levels. Default: 5.
  • Wwt — [full] — Wavelet transform mode. Default: full.
  • Wcboff — <x y> — Code-block partition origin (0 or 1). Default: must be provided (default in usage: 0 0).

Note: Wcboff is required by the forward transform instance creation in the encoder code; typical value: "0 0".

Filters (prefix F)

Source: AnWTFilter.ParameterInfo

  • Ffilters — [<tile-component idx>] <id> — Specifies analysis wavelet filters (e.g. "w5x3" or "w9x7").
    • Default: depends on lossless / quantization type; w5x3 for reversible, w9x7 for non-reversible.

Component transform (prefix M)

Source: ForwCompTransf.ParameterInfo

  • Mct — [<tile index>] [on|off] ... — Multiple component transform (RCT/ICT). Values: on/off, rct/ict in per-tile contexts.
    • Default: not specified (encoder picks rct or ict depending on filters and lossless).

Quantization (prefix Q)

Source: Quantizer.ParameterInfo

  • Qtype — [<tile-component idx>] <id> — Quantization type: reversible, derived, expounded.
    • Default: depends on lossless flag and other defaults.
  • Qstep — [<tile-component idx>] <bnss> — Base normalized quantization step size (ignored in reversible). Default: 0.0078125.
  • Qguard_bits — [<tile-component idx>] <gb> — Number of guard bits. Default: 2.

Rate allocation / layering (prefix A)

Source: PostCompRateAllocator.ParameterInfo

  • Alayers — [<rate> [+<layers>] ... | sl] — Explicit layers specification. Default example in source: "0.015 +20 2.0 +10".
  • Aptype — progression order: res, layer, res-pos, pos-comp, comp-pos (or complex POC syntax). Default: depends on Rroi / other options; typical default is layer.

Notes: Alayers uses internal syntax (rates and optional +<layers>). See code comments in PostCompRateAllocator for parsing rules.

Other encoder modules and options

  • Progression/poc options are handled via Aptype and related POC syntax.
  • Entropy/packet options: Clen_calc, Cterm_type, Cseg_symbol etc. — configured via encoder specs; see EncoderSpecs and the specific ModuleSpec classes in code.

Where to find authoritative lists (in this repository)

  • CoreJ2K/J2kImage.cs — encoder_pinfo (general encoder options)
  • CoreJ2K/j2k/wavelet/analysis/ForwardWT.cs — W options (Wlev, Wwt, Wcboff)
  • CoreJ2K/j2k/wavelet/analysis/AnWTFilter.cs — Ffilters
  • CoreJ2K/j2k/image/forwcomptransf/ForwCompTransf.cs — Mct
  • CoreJ2K/j2k/quantization/quantizer/Quantizer.cs — Qtype, Qstep, Qguard_bits
  • CoreJ2K/j2k/entropy/encoder/PostCompRateAllocator.cs — Alayers, Aptype

Use those files as the canonical source of parameter names and default values.

Quick recipes

  • Lossy, JP2 wrapped, tiled 1024×1024, 5-level WT at 0.5 bpp
var p = new ParameterList();
p["rate"] = "0.5";
p["file_format"] = "on";
p["tiles"] = "1024 1024";
p["Wlev"] = "5";
var bytes = J2kImage.ToBytes(bitmap, p);
  • Lossless JP2
var p = new ParameterList();
p["lossless"] = "on";
p["file_format"] = "on";
var bytes = J2kImage.ToBytes(bitmap, p);