Content Comparison

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OpenJPEG is an open-source JPEG 2000 codec written in C. There is no GUI. This command-line tool is easy to run and maintain using a command-line friendly OS like Linux, so I recommend installing Linux on your Windows 10 1X machine, taking advantage of W10's Windows Subsystem for Linux feature.

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The process of compiling Grok is so fussy that, as of March 2023January 2024, we recommend:

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sudo apt-get install libgrokj2k1 grokj2k-tools libgrokj2k1-dev libgrokj2k1-doc

5. Test your installation

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• jpylyzer *.jp2 | grep '<isValid format="jp2">True</isValid>'

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Encoding JP2 files

Command: opj_compress

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, OpenJPEG

• Switches, partial list:

  • -i <inputFile.ext>
  • -p RLCP (progression order)
  • -t 1024,1024 (tile size, width,height)
  • -EPH (End of Packet Header marker)
  • -SOP (Start of Packet)
  • -ImgDir <image dir> (cannot be used with -i switch)
  • -OutFor <ext> (extension for output files)
  • -o <outputFile.ext>
  • -I (specifies lossy encoding)
  • -q <quality in db>
  • -r <compression ratio>
  • -OutFor [J2K|J2C|JP2]

  Output format used to compress the images read from the directory specified with-ImgDir. Required when-ImgDiroption is used. Supported formats areJ2K,J2C, andJP2.

  • -InFor [pbm|pgm|ppm|pnm|pam|pgx|png|bmp|tif|raw|rawl|jpg]

  Input format. Will override file tag.

Selected Grok-specific switches

(See: Options for complete list)

• -logfile [output file name]

Log to file. File name will be set tooutput file name

• -num_threads [number of threads]

Number of threads used for T1 compression. Default is total number of logical cores.

• -Comment [comment]

Add <comment> in comment marker segment(s). Multiple comments (up to a total of 256) can be specified, separated by the | character. For example: -C "This is my first comment|This is my second will store This is my first comment in the first comment marker segment, and This is my second in a second comment marker.

• -Q, -CaptureRes [capture resolution X,capture resolution Y]

Capture resolution in pixels/metre, in double precision.

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Command: grk_compress, Grok

• Switches, partial list:
  • -i <inputFile.ext>
  • -p RLCP (progression order)
  • -t 1024,1024 (tile size, [width,height])
  • -EPH (End of Packet Header marker)
  • -SOP (Start of Packet)
  • -batch_src <input dir> (cannot be used with -i switch)
  • -out_dir <output dir> (required with batch_src is used)
  • -o <outputFile.ext>
  • -I (specifies lossy encoding)
  • -q <quality in db>
  • -r <compression ratio>
  • -out_fmt [J2K|J2C|JP2]
  • -V (transfer Exif tags)
  • -logfile <output file name>
  • -num_threads <number of threads>
  • -comment <comment>

Lossless example

• opj_compress -i in.tif -o out_lossless.jp2 -p RLCP -t 1024,1024 -EPH -SOP

• grk_compress -i in.tif -o grk_out_lossless.jp2 -p RLCP -t 1024,1024 -EPH -SOP

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• grk_decompress -i infile.j2k -o outfile.png

• grk_decompress -ImgDir batch_src images/ -OutFor out_fmt tif

—

Encoding entire directories

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#!/bin/bash
#Grok Image Compression JP2 JPEG2000 codec encoder lossy compression
#https://github.com/GrokImageCompression/grok
find . -type f | grep --extended-regexp ".*\.tif$" | sed -E "s/.tif//g" > tiffNameStem.txt
ls -1 *.tif | wc -l | xargs echo "TIFF count: "
while read line
do
    grk_compress -i $line".tif" -o $line"_lossy.jp2" -p RLCP -t 1024,1024 -EPH -SOP -I -q 42
    echo "converting "$line".tif"
done < tiffNameStem.txt
echo "
     ~~~ FIN ~~~
"
ls -1 *.jp2 | wc -l | xargs echo "JP2 count: "

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end