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Automated JP2 profiling for digitisation batches

Project description

Jprofile

What is jprofile?

Jprofile is a simple tool for automated profiling of large batches of JP2 (JPEG 2000 part 1) images. Internally it wraps around jpylyzer, which is used for validating each image and for extracting its properties. The jpylyzer output is then validated against a set of Schematron schemas that contain the required characteristics for master, access and target images, respectively.

Installation

The easiest method to install Jprofile is to use the pip package manager. Alternatively, Windows users can also use stand-alone binaries that don't require Python at all (see below).

Installation with pip (single user)

This will work on any platform for which Python is available. You need a recent version of pip (version 9.0 or more recent). To install Jprofile for a single user, use the following command:

pip install jprofile --user

Installation with pip (all users)

To install Jprofile for all users, use the following command:

pip install jprofile

You need local admin (Windows) / superuser (Linux) privilige to do this. On Windows, you can do this by running the above command in a Command Prompt window that was opened as Administrator. On Linux, use this:

sudo pip install jprofile

Installation of Windows binaries

For Windows users who don't have Python available on their system, stand-alone binaries of Jprofile are available. In this case the installation steps are:

  1. Download the latest binaries (64 or 32 bit) from the latest release page .

  2. Unzip the downloaded file to an empty directory.

Command-line syntax

usage: jprofile batchDir prefixOut -p PROFILE

Positional arguments

batchDir: root directory of batch

prefixOut: prefix that is used for writing output files

PROFILE: name of profile that defines schemas for master, access and target images

To list all available profiles, use a value of l or list for PROFILE.

Batch structure

Jprofile was designed for processing digitisation batches that are delivered to the KB by external suppliers. These batches typically contain (losslessly compressed) master JP2s, (lossily compressed) access JP2s and (sometimes) also technical target JP2s. These are located in a folder structure that contains (sub) directories named master, access and targets-jp2, respectively. Below is an example:

./testbatch
├── access
│   ├── IMAGE000060.jp2
│   ├── IMAGE000061.jp2
│   ├── IMAGE000062.jp2
│   ├── ::
│   ├── IMAGE000080.jp2
│   └── IMAGE000081.jp2
├── master
│   ├── IMAGE000060.jp2
│   ├── IMAGE000061.jp2
│   ├── IMAGE000062.jp2
│   ├── ::
│   ├── IMAGE000080.jp2
│   └── IMAGE000081.jp2
└── targets-jp2

As long as a batch follows this basic structure, Jprofile can handle it. Note that:

  • master, access and targets-jp2 directories may occur at different nesting levels. This is no problem, since profile recursively traverses all subdirctories in a batch.

  • if either a master, access or targets-jp2 directory is missing, jprofile will simply ignore it (i.e. it's perfectly OK if your batch only contains master images).

  • Batches may contain other folders. These are ignored by jprofile.

Profiles

A profile is an XML-formatted file that simply defines which schemas are used to validate jpylyzer's output for master, access and target images, respectively. Here's an example:

<profile>

<!-- Sample profile -->

<schemaMaster>master300Gray_2014.sch</schemaMaster>
<schemaAccess>access300Colour_2014.sch</schemaAccess>
<schemaTarget>master300Colour_2014.sch</schemaTarget>

</profile>

Note that each entry only contains the name of a profile, not its full path! All profiles are located in the profiles directory in the installation folder.

Available profiles

The following profiles are included by default:

Name Description
kb_generic_2014.xml Generic profile for KB digitisation streams (doesn't include any checks on resolution or colour spaces!)
kb_300Colour_2014.xml As generic profile, but with additional requirements on resolution (must be equal to 300 ppi) and colour space (must be Adobe RGB 1998)
kb_300Gray_2014.xml As generic profile, but with additional requirements on resolution (must be equal to 300 ppi) and colour space (must be Gray Gamma 2.2)
kb_600Colour_2014.xml As generic profile, but with additional requirements on resolution (must be equal to 600 ppi) and colour space (must be Adobe RGB 1998)
kb_600Gray_2014.xml As generic profile, but with additional requirements on resolution (must be equal to 600 ppi) and colour space (must be Gray Gamma 2.2)

It is possible to create custom-made profiles. Just add them to the profiles directory in the installation folder.

Schemas

The quality assessment is based on a number of rules/tests that are defined a set of Schematron schemas. These are located in the schemas folder in the installation directory. In principle any property that is reported by jpylyzer can be used here, and new tests can be added by editing the schemas. More details on this can be found in this blog post.

Available schemas

Name Description
kbMaster_2014.sch Generic schema for losslessly-compressed master images according to 2014 specifications
master600Colour_2014.sch Schema for losslessly-compressed master images, 600 ppi, Adobe RGB (1998) colour space
master600Gray_2014.sch Schema for losslessly-compressed master images, 600 ppi, Gray Gamma 2.2 colour space
master300Colour_2014.sch Schema for losslessly-compressed master images, 300 ppi, Adobe RGB (1998) colour space
master300Gray_2014.sch Schema for losslessly-compressed master images, 300 ppi, Gray Gamma 2.2 colour space
kbAccess_2014.sch Generic schema for lossily-compressed access images according to 2014 specifications
access600Colour_2014.sch Schema for lossily-compressed access images, 600 ppi, Adobe RGB (1998) colour space
access600Gray_2014.sch Schema for lossily-compressed access images, 600 ppi, Gray Gamma 2.2 colour space
access300Colour_2014.sch Schema for lossily-compressed access images, 300 ppi, Adobe RGB (1998) colour space
access300Gray_2014.sch Schema for lossily-compressed access images, 300 ppi, Gray Gamma 2.2 colour space

It is possible to create custom-made schemas. Just add them to the schemas directory in the installation folder.

Overview of 2014 schemas

The following tables give a general overview of the technical profiles that the generic master- and access schemas are representing:

Master

Parameter Value
File format JP2 (JPEG 2000 Part 1)
Compression type Reversible 5-3 wavelet filter
Colour transform Yes (only for colour images)
Number of decomposition levels 5
Progression order RPCL
Tile size 1024 x 1024
Code block size 64 x 64 (26 x 26)
Precinct size 256 x 256 (28) for 2 highest resolution levels; 128 x 128 (27) for remaining resolution levels
Number of quality layers 11
Target compression ratio layers 2560:1 [1] ; 1280:1 [2] ; 640:1 [3] ; 320:1 [4] ; 160:1 [5] ; 80:1 [6] ; 40:1 [7] ; 20:1 [8] ; 10:1 [9] ; 5:1 [10] ; 2.5:1 [11]
Error resilience Start-of-packet headers; end-of-packet headers; segmentation symbols
Sampling rate Stored in "Capture Resolution" fields
Capture metadata Embedded as XMP metadata in XML box

Access

Parameter Value
File format JP2 (JPEG 2000 Part 1)
Compression type Irreversible 7-9 wavelet filter
Colour transform Yes (only for colour images)
Number of decomposition levels 5
Progression order RPCL
Tile size 1024 x 1024
Code block size 64 x 64 (26 x 26)
Precinct size 256 x 256 (28) for 2 highest resolution levels; 128 x 128 (27) for remaining resolution levels
Number of quality layers 8
Target compression ratio layers 2560:1 [1] ; 1280:1 [2] ; 640:1 [3] ; 320:1 [4] ; 160:1 [5] ; 80:1 [6] ; 40:1 [7] ; 20:1 [8]
Error resilience Start-of-packet headers; end-of-packet headers; segmentation symbols
Sampling rate Stored in "Capture Resolution" fields
Capture metadata Embedded as XMP metadata in XML box

Note that jpylyzer is unable to establish the compression ratio of individual layers, so the access schema only checks for the overall compression ratio (i.e. 20:1). The more specific schemas (300Colour, 600Gray, etc.) contain additional checks for resolution values, the number of colour components and embedded ICC profiles.

Usage examples

List available profiles

jprofile d:\myBatch mybatch -p list

This results in a list of all available profiles (these are stored in the installation folder's profiles directory):

Available profiles:

kb_600Gray_2014.xml
kb_300Gray_2014.xml
kb_300Colour_2014.xml
kb_600Colour_2014.xml
kb_generic_2014.xml

Analyse batch

jprofile d:\myBatch mybatch -p kb_300Colour_2014.xml

This will result in the creation of 2 output files:

  • mybatch_status.csv (status output file)
  • mybatch_failed.txt (detailed output on images that failed quality asessment)

Status output file

This is a comma-separated file with the assessment status of each analysed image. The assessment status is either pass (passed all tests) or fail (failed one or more tests). Here's an example:

F:\test\access\MMKB03_000004896_00015_access.jp2,pass
F:\test\access\MMKB03_000004896_00115_access.jp2,pass
F:\test\access\MMKB03_000004896_00215_access.jp2,pass
F:\test\targets-jp2\MMKB03_MTF_RGB_20120626_02_01.jp2,fail
F:\test\master\MMKB03_000004896_00015_master.jp2,pass

Failure output file

Any image that failed one or more tests are reported in the failure output file. For each failed image, it contains a full reference to the file path, followed by the specific errors. An example:

F:\test\targets-jp2\MMKB03_MTF_RGB_20120626_02_01.jp2
*** Schema validation errors:
Test "layers = '11'" failed (wrong number of layers)
Test "transformation = '5-3 reversible'" failed (wrong transformation)
Test "comment = 'KB_MASTER_LOSSLESS_01/01/2015'" failed (wrong codestream comment string)
####

Entries in this file are separated by a sequence of 4 '#' characters. Note that each line here corresponds to a failed test in the schema. For images that are identified as not-valid JP2 some additional information from jpylyzer's output is included as well. For example:

F:\test\master\MMUBL07_MTF_GRAY_20121213_01_05.jp2
*** Schema validation errors:
Test "isValidJP2 = 'True'" failed (no valid JP2)
*** Jpylyzer JP2 validation errors:
Test methIsValid failed
Test precIsValid failed
Test approxIsValid failed
Test foundNextTilePartOrEOC failed
Test foundEOCMarker failed
####

Here, the outcome of test isValidJP2 means that the image does not conform to the JP2 specification. The lines following 'Jpylyzer JP2 validation errors' lists the specific errors that were reported by jpylyzer. The meaning of these errors can be found in the jpylyzer User Manual.

Preconditions

  • All images that are to be analysed have a .jp2 extension (all others are ignored!)
  • Master images are located in a (subdirectory of a) directory called 'master'
  • Access images are located in a (subdirectory of a) directory called 'access'
  • Target images are located in a (subdirectory of a) directory called 'targets-jp2'.
  • Either of the above directories may be missing.

Other than that, the organisation of images may follow any arbitrary directory structure (jprofile does a recursive scan of whole directory tree of a batch).

Known limitations

  • Images that have names containing square brackets ("[" and "]" are ignored (limitation of Python's glob module, will be solved in the future).

Licensing

Jprofile is released under the GNU Lesser General Public License.

Useful links

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