openhtj2kenc

Part 15 (HTJ2K) compliant encoder. Produces either a raw codestream (.j2c, .jhc) or an HTJ2K JPH file (.jph). Accepts PGM, PPM, PGX, and TIFF (with libtiff) inputs. The default streaming path handles all four formats — PGX with subsampled component sets (4:2:2, 4:2:0) and basic TIFF (8/16-bit, RGB or grayscale, single-strip or strip-compressed). Tiled TIFFs require -batch.

Full runtime help: open_htj2k_enc -h.

Synopsis

open_htj2k_enc -i <input-image(s)> -o <output> [options...]

Multiple input files can be passed as a comma-separated list. For example, to encode separate YCbCr component files:

open_htj2k_enc -i inputY.pgx,inputCb.pgx,inputCr.pgx -o output

-o takes the base name; the extension decides the container: .j2c / .jhc for raw HTJ2K codestream, .jph for the JPH file format.

Options

Tile and image structure

• Stiles=Size
  • Tile size in {height,width} format. Default is equal to the image size.
• Sorigin=Size
  • Offset from the reference grid origin to the image area. Default is {0,0}.
• Stile_origin=Size
  • Offset from the reference grid origin to the first tile. Default is {0,0}.

DWT and codeblock structure

• Clevels=Int
  • Number of DWT decomposition levels. Valid range: 0–32. Default is 5.
• Creversible=yes|no
  • yes for lossless mode, no for lossy mode. Default is no.
• Cblk=Size
  • Code-block size. Default is {64,64}.
• Cprecincts=Size
  • Precinct size. Must be a power of two.
• Cycc=yes|no
  • yes to apply RGB→YCbCr color space conversion. Default is yes.
• Corder=<LRCP|RLCP|RPCL|PCRL|CPRL>
  • Progression order. Default is LRCP.
• Cuse_sop=yes|no
  • yes to insert SOP (Start Of Packet) marker segments. Default is no.
• Cuse_eph=yes|no
  • yes to insert EPH (End of Packet Header) markers. Default is no.

Quantization and quality

• Qstep=Float
  • Base step size for quantization. Valid range: 0.0 < Qstep <= 2.0.
• Qguard=Int
  • Number of guard bits. Valid range: 0–8. Default is 1.
• Qfactor=Int
  • Quality factor for lossy compression. Valid range: 0–100 (100 = best quality).
  • When specified, Qstep is ignored and Cycc is set to yes.

JPH and component layout

• -jph_color_space RGB|YCC
  • Declare the color space of the input components. Use YCC if the inputs are already in YCbCr.

Runtime

• -num_threads Int
  • Number of threads. 0 (default) uses all available hardware threads.
• -batch
  • Use the batch (full-image) encode path. Loads the entire image into memory before encoding. The default path is line-based (streaming).

Examples

# Lossless encode, default DWT / codeblock settings
open_htj2k_enc -i input.ppm -o out.j2c Creversible=yes

# Lossy encode at quality 90, write to JPH file format
open_htj2k_enc -i input.ppm -o out.jph Qfactor=90

# Encode YCbCr components into a JPH file with explicit color space
open_htj2k_enc -i Y.pgx,Cb.pgx,Cr.pgx -o out.jph -jph_color_space YCC

# Lossless encode with 6 DWT levels and RPCL progression
open_htj2k_enc -i input.ppm -o out.j2c Creversible=yes Clevels=6 Corder=RPCL