How do I…?¶
… read images?¶
Jp2k implements slicing via the __getitem__() method and
hooks it into the multiple resolution property of JPEG 2000 imagery.
This means that lower-resolution imagery can be accessed via
array-style slicing that utilizes strides. For example here’s how
to retrieve a full resolution and first lower-resolution image
>>> import glymur
>>> jp2file = glymur.data.nemo() # just a path to a JPEG2000 file
>>> jp2 = glymur.Jp2k(jp2file)
>>> fullres = jp2[:]
>>> fullres.shape
(1456, 2592, 3)
>>> thumbnail = jp2[::2, ::2]
>>> thumbnail.shape
(728, 1296, 3)
… make use of OpenJPEG’s thread support to read images?¶
If you have glymur 0.8.13 or higher and OpenJPEG 2.2.0 or higher, you can make use of OpenJPEG’s thread support to speed-up read operations
>>> import glymur
>>> import time
>>> jp2file = glymur.data.nemo()
>>> jp2 = glymur.Jp2k(jp2file)
>>> t0 = time.time(); data = jp2[:]; t1 = time.time()
>>> t1 - t0
0.9024193286895752
>>> glymur.set_option('lib.num_threads', 2)
>>> t0 = time.time(); data = jp2[:]; t1 = time.time()
>>> t1 - t0
0.4060473537445068
… write images?¶
It’s pretty simple, just supply the image data as a keyword argument to the Jp2k constructor.
>>> import glymur, numpy as np
>>> jp2 = glymur.Jp2k('zeros.jp2', data=np.zeros((640, 480), dtype=np.uint8))
You must have OpenJPEG version 1.5 or more recent in order to write JPEG 2000 images with glymur.
… write images with different compression ratios for different layers?¶
Different compression factors may be specified with the cratios parameter
>>> import skimage.data, glymur
>>> data = skimage.data.camera()
>>> # quality layer 1: compress 20x
>>> # quality layer 2: compress 10x
>>> # quality layer 3: compress lossless
>>> jp2 = glymur.Jp2k('myfile.jp2', data=data, cratios=[20, 10, 1])
>>> # read the lossless layer
>>> jp2.layer = 2
>>> data = jp2[:]
… write images with different PSNR (or “quality”) for different layers?¶
Different PSNR values may be specified with the psnr parameter. Please read https://en.wikipedia.org/wiki/Peak_signal-to-noise_ratio for a basic understanding of PSNR.
Values must be increasing, but the last value may be 0 to indicate the layer is lossless. However, the OpenJPEG library will reorder the layers to make the first layer lossless, not the last.
>>> import skimage.data, skimage.measure, glymur
>>> truth = skimage.data.camera()
>>> jp2 = glymur.Jp2k('myfile.jp2', data=truth, psnr=[30, 40, 50, 0])
>>> psnr = []
>>> for layer in range(4):
... jp2.layer = layer
... psnr.append(skimage.measure.compare_psnr(truth, jp2[:]))
>>> print(psnr)
[inf, 29.028560403833303, 39.206919416670402, 47.593129828702246]
… display metadata?¶
There are two ways. From the command line, the console script jp2dump is available.
$ jp2dump /path/to/glymur/installation/data/nemo.jp2
From within Python, the same result is obtained simply by printing the Jp2k object, i.e.
>>> import glymur
>>> jp2file = glymur.data.nemo() # just a path to a JP2 file
>>> jp2 = glymur.Jp2k(jp2file)
>>> print(jp2)
File: nemo.jp2
JPEG 2000 Signature Box (jP ) @ (0, 12)
Signature: 0d0a870a
File Type Box (ftyp) @ (12, 20)
Brand: jp2
Compatibility: ['jp2 ']
JP2 Header Box (jp2h) @ (32, 45)
Image Header Box (ihdr) @ (40, 22)
Size: [1456 2592 3]
Bitdepth: 8
Signed: False
Compression: wavelet
Colorspace Unknown: False
Colour Specification Box (colr) @ (62, 15)
Method: enumerated colorspace
Precedence: 0
Colorspace: sRGB
UUID Box (uuid) @ (77, 3146)
UUID: be7acfcb-97a9-42e8-9c71-999491e3afac (XMP)
UUID Data:
<ns0:xmpmeta xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:ns0="adobe:ns:meta/" xmlns:ns2="http://ns.adobe.com/xap/1.0/" xmlns:ns3="http://ns.adobe.com/tiff/1.0/" xmlns:ns4="http://ns.adobe.com/exif/1.0/" xmlns:ns5="http://ns.adobe.com/photoshop/1.0/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" ns0:xmptk="Exempi + XMP Core 5.1.2">
<rdf:RDF>
<rdf:Description rdf:about="">
<ns2:CreatorTool>Google</ns2:CreatorTool>
<ns2:CreateDate>2013-02-09T14:47:53</ns2:CreateDate>
</rdf:Description>
<rdf:Description rdf:about="">
<ns3:YCbCrPositioning>1</ns3:YCbCrPositioning>
<ns3:XResolution>72/1</ns3:XResolution>
<ns3:YResolution>72/1</ns3:YResolution>
<ns3:ResolutionUnit>2</ns3:ResolutionUnit>
<ns3:Make>HTC</ns3:Make>
<ns3:Model>HTC Glacier</ns3:Model>
<ns3:ImageWidth>2592</ns3:ImageWidth>
<ns3:ImageLength>1456</ns3:ImageLength>
<ns3:BitsPerSample>
<rdf:Seq>
<rdf:li>8</rdf:li>
<rdf:li>8</rdf:li>
<rdf:li>8</rdf:li>
</rdf:Seq>
</ns3:BitsPerSample>
<ns3:PhotometricInterpretation>2</ns3:PhotometricInterpretation>
<ns3:SamplesPerPixel>3</ns3:SamplesPerPixel>
<ns3:WhitePoint>
<rdf:Seq>
<rdf:li>1343036288/4294967295</rdf:li>
<rdf:li>1413044224/4294967295</rdf:li>
</rdf:Seq>
</ns3:WhitePoint>
<ns3:PrimaryChromaticities>
<rdf:Seq>
<rdf:li>2748779008/4294967295</rdf:li>
<rdf:li>1417339264/4294967295</rdf:li>
<rdf:li>1288490240/4294967295</rdf:li>
<rdf:li>2576980480/4294967295</rdf:li>
<rdf:li>644245120/4294967295</rdf:li>
<rdf:li>257698032/4294967295</rdf:li>
</rdf:Seq>
</ns3:PrimaryChromaticities>
</rdf:Description>
<rdf:Description rdf:about="">
<ns4:ColorSpace>1</ns4:ColorSpace>
<ns4:PixelXDimension>2528</ns4:PixelXDimension>
<ns4:PixelYDimension>1424</ns4:PixelYDimension>
<ns4:FocalLength>353/100</ns4:FocalLength>
<ns4:GPSAltitudeRef>0</ns4:GPSAltitudeRef>
<ns4:GPSAltitude>0/1</ns4:GPSAltitude>
<ns4:GPSMapDatum>WGS-84</ns4:GPSMapDatum>
<ns4:DateTimeOriginal>2013-02-09T14:47:53</ns4:DateTimeOriginal>
<ns4:ISOSpeedRatings>
<rdf:Seq>
<rdf:li>76</rdf:li>
</rdf:Seq>
</ns4:ISOSpeedRatings>
<ns4:ExifVersion>0220</ns4:ExifVersion>
<ns4:FlashpixVersion>0100</ns4:FlashpixVersion>
<ns4:ComponentsConfiguration>
<rdf:Seq>
<rdf:li>1</rdf:li>
<rdf:li>2</rdf:li>
<rdf:li>3</rdf:li>
<rdf:li>0</rdf:li>
</rdf:Seq>
</ns4:ComponentsConfiguration>
<ns4:GPSLatitude>42,20.56N</ns4:GPSLatitude>
<ns4:GPSLongitude>71,5.29W</ns4:GPSLongitude>
<ns4:GPSTimeStamp>2013-02-09T19:47:53Z</ns4:GPSTimeStamp>
<ns4:GPSProcessingMethod>NETWORK</ns4:GPSProcessingMethod>
</rdf:Description>
<rdf:Description rdf:about="">
<ns5:DateCreated>2013-02-09T14:47:53</ns5:DateCreated>
</rdf:Description>
<rdf:Description rdf:about="">
<dc:Creator>
<rdf:Seq>
<rdf:li>Glymur</rdf:li>
<rdf:li>Python XMP Toolkit</rdf:li>
</rdf:Seq>
</dc:Creator>
</rdf:Description>
</rdf:RDF>
</ns0:xmpmeta>
Contiguous Codestream Box (jp2c) @ (3223, 1132296)
Main header:
SOC marker segment @ (3231, 0)
SIZ marker segment @ (3233, 47)
Profile: 2
Reference Grid Height, Width: (1456 x 2592)
Vertical, Horizontal Reference Grid Offset: (0 x 0)
Reference Tile Height, Width: (1456 x 2592)
Vertical, Horizontal Reference Tile Offset: (0 x 0)
Bitdepth: (8, 8, 8)
Signed: (False, False, False)
Vertical, Horizontal Subsampling: ((1, 1), (1, 1), (1, 1))
COD marker segment @ (3282, 12)
Coding style:
Entropy coder, without partitions
SOP marker segments: False
EPH marker segments: False
Coding style parameters:
Progression order: LRCP
Number of layers: 2
Multiple component transformation usage: reversible
Number of resolutions: 2
Code block height, width: (64 x 64)
Wavelet transform: 5-3 reversible
Precinct size: default, 2^15 x 2^15
Code block context:
Selective arithmetic coding bypass: False
Reset context probabilities on coding pass boundaries: False
Termination on each coding pass: False
Vertically stripe causal context: False
Predictable termination: False
Segmentation symbols: False
QCD marker segment @ (3296, 7)
Quantization style: no quantization, 2 guard bits
Step size: [(0, 8), (0, 9), (0, 9), (0, 10)]
CME marker segment @ (3305, 37)
"Created by OpenJPEG version 2.0.0"
That’s fairly overwhelming, and perhaps lost in the flood of information
is the fact that the codestream metadata is limited to just what’s in the
main codestream header. You can suppress the codestream and XML details by
making use of the set_option() function:
>>> glymur.set_option('print.codestream', False)
>>> glymur.set_option('print.xml', False)
>>> print(jp2)
File: nemo.jp2
JPEG 2000 Signature Box (jP ) @ (0, 12)
Signature: 0d0a870a
File Type Box (ftyp) @ (12, 20)
Brand: jp2
Compatibility: ['jp2 ']
JP2 Header Box (jp2h) @ (32, 45)
Image Header Box (ihdr) @ (40, 22)
Size: [1456 2592 3]
Bitdepth: 8
Signed: False
Compression: wavelet
Colorspace Unknown: False
Colour Specification Box (colr) @ (62, 15)
Method: enumerated colorspace
Precedence: 0
Colorspace: sRGB
UUID Box (uuid) @ (77, 3146)
UUID: be7acfcb-97a9-42e8-9c71-999491e3afac (XMP)
Contiguous Codestream Box (jp2c) @ (3223, 1132296)
It is possible to easily print the codestream header details as well, i.e.
>>> print(j.codestream) # details not show
… add XML metadata?¶
You can append any number of XML boxes to a JP2 file (not to a raw codestream). Consider the following XML file data.xml :
<?xml version="1.0"?>
<info>
<locality>
<city>Boston</city>
<snowfall>24.9 inches</snowfall>
</locality>
<locality>
<city>Portland</city>
<snowfall>31.9 inches</snowfall>
</locality>
<locality>
<city>New York City</city>
<snowfall>11.4 inches</snowfall>
</locality>
</info>
The append() method can add an XML box as shown below:
>>> import shutil
>>> import glymur
>>> shutil.copyfile(glymur.data.nemo(), 'myfile.jp2')
>>> jp2 = glymur.Jp2k('myfile.jp2')
>>> xmlbox = glymur.jp2box.XMLBox(filename='data.xml')
>>> jp2.append(xmlbox)
>>> print(jp2)
… add metadata in a more general fashion?¶
An existing raw codestream (or JP2 file) can be wrapped (re-wrapped) in a
user-defined set of JP2 boxes. To get just a minimal JP2 jacket on the
codestream provided by goodstuff.j2k (a file consisting of a raw codestream),
you can use the wrap() method with no box argument:
>>> import glymur
>>> glymur.set_option('print.codestream', False)
>>> jp2file = glymur.data.goodstuff()
>>> j2k = glymur.Jp2k(jp2file)
>>> jp2 = j2k.wrap("newfile.jp2")
>>> print(jp2)
File: newfile.jp2
JPEG 2000 Signature Box (jP ) @ (0, 12)
Signature: 0d0a870a
File Type Box (ftyp) @ (12, 20)
Brand: jp2
Compatibility: ['jp2 ']
JP2 Header Box (jp2h) @ (32, 45)
Image Header Box (ihdr) @ (40, 22)
Size: [800 480 3]
Bitdepth: 8
Signed: False
Compression: wavelet
Colorspace Unknown: False
Colour Specification Box (colr) @ (62, 15)
Method: enumerated colorspace
Precedence: 0
Colorspace: sRGB
Contiguous Codestream Box (jp2c) @ (77, 115228)
The raw codestream was wrapped in a JP2 jacket with four boxes in the outer layer (the signature, file type, JP2 header, and contiguous codestream), with two additional boxes (image header and color specification) contained in the JP2 header superbox.
XML boxes are not in the minimal set of box requirements for the JP2 format, so in order to add an XML box into the mix before the codestream box, we’ll need to re-specify all of the boxes. If you already have a JP2 jacket in place, you can just reuse that, though. Take the following example content in an XML file favorites.xml :
<?xml version="1.0"?>
<favorite_things>
<category>Light Ale</category>
</favorite_things>
In order to add the XML after the JP2 header box, but before the codestream box, the following will work.
>>> boxes = jp2.box # The box attribute is the list of JP2 boxes
>>> xmlbox = glymur.jp2box.XMLBox(filename='favorites.xml')
>>> boxes.insert(3, xmlbox)
>>> jp2_xml = jp2.wrap("newfile_with_xml.jp2", boxes=boxes)
>>> print(jp2_xml)
File: newfile_with_xml.jp2
JPEG 2000 Signature Box (jP ) @ (0, 12)
Signature: 0d0a870a
File Type Box (ftyp) @ (12, 20)
Brand: jp2
Compatibility: ['jp2 ']
JP2 Header Box (jp2h) @ (32, 45)
Image Header Box (ihdr) @ (40, 22)
Size: [800 480 3]
Bitdepth: 8
Signed: False
Compression: wavelet
Colorspace Unknown: False
Colour Specification Box (colr) @ (62, 15)
Method: enumerated colorspace
Precedence: 0
Colorspace: sRGB
XML Box (xml ) @ (77, 76)
<favorite_things>
<category>Light Ale</category>
</favorite_things>
Contiguous Codestream Box (jp2c) @ (153, 115236)
As to the question of which method you should use, append() or
wrap(), to add metadata, you should keep in mind that wrap()
produces a new JP2 file, while append() modifies an existing file and
is currently limited to XML and UUID boxes.
… work with ICC profiles?¶
A detailed answer is beyond my capabilities. What I can tell you is how to
gain access to ICC profiles that JPEG 2000 images may or may not provide for
you. If there is an ICC profile, it will be provided in a ColourSpecification
box, but only if the colorspace attribute is None. Here is an example
of how you can access an ICC profile in an example JPX file.
Basically what is done is that the raw bytes corresponding to the ICC profile
are wrapped in a BytesIO object, which is fed to the most-excellent Pillow package.
>>> from glymur import Jp2k
>>> from PIL import ImageCms
>>> from io import BytesIO
>>> # This next step produces a harmless warning that has nothing to do with ICC profiles.
>>> j = Jp2k('text_GBR.jp2')
>>> # The 2nd sub box of the 4th box is a ColourSpecification box.
>>> print(j.box[3].box[1].colorspace)
None
>>> b = BytesIO(j.box[3].box[1].icc_profile_data)
>>> icc = ImageCms.ImageCmsProfile(b)
To go any further with this, you will want to consult the Pillow documentation.
… create an image with an alpha layer?¶
OpenJPEG can create JP2 files with more than 3 components (use version 2.1.0+ for this), but by default, any extra components are not described as such. In order to do so, we need to re-wrap such an image in a set of boxes that includes a channel definition box.
This example is based on SciPy example code found at http://scipy-lectures.org/advanced/image_processing/#basic-manipulations . Instead of a circular mask we’ll make it an ellipse since the source image isn’t square.
>>> import numpy as np
>>> import glymur
>>> from glymur import Jp2k
>>> rgb = Jp2k(glymur.data.goodstuff())[:]
>>> lx, ly = rgb.shape[0:2]
>>> X, Y = np.ogrid[0:lx, 0:ly]
>>> mask = ly**2*(X - lx / 2) ** 2 + lx**2*(Y - ly / 2) ** 2 > (lx * ly / 2)**2
>>> alpha = 255 * np.ones((lx, ly, 1), dtype=np.uint8)
>>> alpha[mask] = 0
>>> rgba = np.concatenate((rgb, alpha), axis=2)
>>> jp2 = Jp2k('tmp.jp2', data=rgba)
Next we need to specify what types of channels we have. The first three channels are color channels, but we identify the fourth as an alpha channel:
>>> from glymur.core import COLOR, OPACITY
>>> ctype = [COLOR, COLOR, COLOR, OPACITY]
And finally we have to specify just exactly how each channel is to be interpreted. The color channels are straightforward, they correspond to R-G-B, but the alpha (or opacity) channel in this case is to be applied against the entire image (it is possible to apply an alpha channel to a single color channel, but we aren’t doing that).
>>> from glymur.core import RED, GREEN, BLUE, WHOLE_IMAGE
>>> asoc = [RED, GREEN, BLUE, WHOLE_IMAGE]
>>> cdef = glymur.jp2box.ChannelDefinitionBox(ctype, asoc)
>>> print(cdef)
Channel Definition Box (cdef) @ (0, 0)
Channel 0 (color) ==> (1)
Channel 1 (color) ==> (2)
Channel 2 (color) ==> (3)
Channel 3 (opacity) ==> (whole image)
It’s easiest to take the existing jp2 jacket and just add the channel definition box in the appropriate spot. The channel definition box must go into the jp2 header box, and then we can rewrap the image.
>>> boxes = jp2.box # The box attribute is the list of JP2 boxes
>>> boxes[2].box.append(cdef)
>>> jp2_rgba = jp2.wrap("goodstuff_rgba.jp2", boxes=boxes)
Here’s how the Preview application on the mac shows the RGBA image.
… work with XMP UUIDs?¶
Wikipedia states that “The Extensible Metadata Platform (XMP) is an ISO standard, originally created by Adobe Systems Inc., for the creation, processing and interchange of standardized and custom metadata for all kinds of resources.”
The example JP2 file shipped with glymur has an XMP UUID.
>>> import glymur
>>> j = glymur.Jp2k(glymur.data.nemo())
>>> print(j.box[3]) # formatting added to the XML below
<ns0:xmpmeta xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns:ns0="adobe:ns:meta/"
xmlns:ns2="http://ns.adobe.com/xap/1.0/"
xmlns:ns3="http://ns.adobe.com/tiff/1.0/"
xmlns:ns4="http://ns.adobe.com/exif/1.0/"
xmlns:ns5="http://ns.adobe.com/photoshop/1.0/"
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
ns0:xmptk="Exempi + XMP Core 5.1.2">
<rdf:RDF>
<rdf:Description rdf:about="">
<ns2:CreatorTool>Google</ns2:CreatorTool>
<ns2:CreateDate>2013-02-09T14:47:53</ns2:CreateDate>
</rdf:Description>
.
.
.
</ns0:xmpmeta>
Since the UUID data in this case is returned as an lxml ElementTree instance, one can use lxml to access the data. For example, to extract the CreatorTool attribute value, one could do the following
>>> xmp = j.box[3].data
>>> rdf = '{http://www.w3.org/1999/02/22-rdf-syntax-ns#}'
>>> ns2 = '{http://ns.adobe.com/xap/1.0/}'
>>> name = '{0}RDF/{0}Description/{1}CreatorTool'.format(rdf, ns2)
>>> elt = xmp.find(name)
>>> elt
<Element '{http://ns.adobe.com/xap/1.0/#}CreatorTool' at 0xb50684a4>
>>> elt.text
'Google'
But that would be painful. A better solution is to install the Python XMP Toolkit (make sure it is at least version 2.0):
>>> from libxmp import XMPMeta
>>> from libxmp.consts import XMP_NS_XMP as NS_XAP
>>> meta = XMPMeta()
>>> meta.parse_from_str(j.box[3].raw_data.decode('utf-8'))
>>> meta.get_property(NS_XAP, 'CreatorTool')
'Google'
Where the Python XMP Toolkit can really shine, though, is when you are converting an image from another format such as TIFF or JPEG into JPEG 2000. For example, if you were to be converting the TIFF image found at http://photojournal.jpl.nasa.gov/tiff/PIA17145.tif info JPEG 2000:
>>> import skimage.io
>>> image = skimage.io.imread('PIA17145.tif')
>>> from glymur import Jp2k
>>> jp2 = Jp2k('PIA17145.jp2', data=image)
Next you can extract the XMP metadata.
>>> from libxmp import XMPFiles
>>> xf = XMPFiles()
>>> xf.open_file('PIA17145.tif')
>>> xmp = xf.get_xmp()
>>> print(xmp)
<?xpacket begin="" id="W5M0MpCehiHzreSzNTczkc9d"?>
<x:xmpmeta xmlns:x="adobe:ns:meta/" x:xmptk="Exempi + XMP Core 5.1.2">
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
<rdf:Description rdf:about=""
xmlns:tiff="http://ns.adobe.com/tiff/1.0/">
<tiff:ImageWidth>1016</tiff:ImageWidth>
<tiff:ImageLength>1016</tiff:ImageLength>
<tiff:BitsPerSample>
<rdf:Seq>
<rdf:li>8</rdf:li>
</rdf:Seq>
</tiff:BitsPerSample>
<tiff:Compression>1</tiff:Compression>
<tiff:PhotometricInterpretation>1</tiff:PhotometricInterpretation>
<tiff:SamplesPerPixel>1</tiff:SamplesPerPixel>
<tiff:PlanarConfiguration>1</tiff:PlanarConfiguration>
<tiff:ResolutionUnit>2</tiff:ResolutionUnit>
</rdf:Description>
<rdf:Description rdf:about=""
xmlns:dc="http://purl.org/dc/elements/1.1/">
<dc:description>
<rdf:Alt>
<rdf:li xml:lang="x-default">converted PNM file</rdf:li>
</rdf:Alt>
</dc:description>
</rdf:Description>
</rdf:RDF>
</x:xmpmeta>
<?xpacket end="w"?>
If you are familiar with TIFF, you can verify that there’s no XMP tag in the TIFF file, but the Python XMP Toolkit takes advantage of the TIFF header structure to populate an XMP packet for you. If you were working with a JPEG file with Exif metadata, that information would be included in the XMP packet as well. Now you can append the XMP packet in a UUIDBox. In order to do this, though, you have to know the UUID that signifies XMP data.:
>>> import uuid
>>> xmp_uuid = uuid.UUID('be7acfcb-97a9-42e8-9c71-999491e3afac')
>>> box = glymur.jp2box.UUIDBox(xmp_uuid, str(xmp).encode())
>>> jp2.append(box)
>>> print(jp2.box[-1])
UUID Box (uuid) @ (592316, 1053)
UUID: be7acfcb-97a9-42e8-9c71-999491e3afac (XMP)
UUID Data:
<ns0:xmpmeta xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:ns0="adobe:ns:meta/" xmlns:ns2="http://ns.adobe.com/tiff/1.0/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" ns0:xmptk="Exempi + XMP Core 5.1.2">
<rdf:RDF>
<rdf:Description rdf:about="">
<ns2:ImageWidth>1016</ns2:ImageWidth>
<ns2:ImageLength>1016</ns2:ImageLength>
<ns2:BitsPerSample>
<rdf:Seq>
<rdf:li>8</rdf:li>
</rdf:Seq>
</ns2:BitsPerSample>
<ns2:Compression>1</ns2:Compression>
<ns2:PhotometricInterpretation>1</ns2:PhotometricInterpretation>
<ns2:SamplesPerPixel>1</ns2:SamplesPerPixel>
<ns2:PlanarConfiguration>1</ns2:PlanarConfiguration>
<ns2:ResolutionUnit>2</ns2:ResolutionUnit>
</rdf:Description>
<rdf:Description rdf:about="">
<dc:description>
<rdf:Alt>
<rdf:li xml:lang="x-default">converted PNM file</rdf:li>
</rdf:Alt>
</dc:description>
</rdf:Description>
</rdf:RDF>
</ns0:xmpmeta>
You can also build up XMP metadata from scratch. For instance, if we try to wrap goodstuff.j2k again:
>>> import glymur
>>> j2kfile = glymur.data.goodstuff()
>>> j2k = glymur.Jp2k(j2kfile)
>>> jp2 = j2k.wrap("goodstuff.jp2")
Now build up the metadata piece-by-piece. It would help to have the XMP standard close at hand:
>>> from libxmp import XMPMeta
>>> from libxmp.consts import XMP_NS_TIFF as NS_TIFF
>>> from libxmp.consts import XMP_NS_DC as NS_DC
>>> xmp = XMPMeta()
>>> ihdr = jp2.box[2].box[0]
>>> xmp.set_property(NS_TIFF, "ImageWidth", str(ihdr.width))
>>> xmp.set_property(NS_TIFF, "ImageHeight", str(ihdr.height))
>>> xmp.set_property(NS_TIFF, "BitsPerSample", '3')
>>> xmp.set_property(NS_DC, "Title", u'Stürm und Drang')
>>> xmp.set_property(NS_DC, "Creator", 'Glymur')
We can then append the XMP in a UUID box just as before:
>>> import uuid
>>> xmp_uuid = uuid.UUID('be7acfcb-97a9-42e8-9c71-999491e3afac')
>>> box = glymur.jp2box.UUIDBox(xmp_uuid, str(xmp).encode())
>>> jp2.append(box)
>>> glymur.set_option('print.codestream', False)
>>> print(jp2)
File: goodstuff.jp2
JPEG 2000 Signature Box (jP ) @ (0, 12)
Signature: 0d0a870a
File Type Box (ftyp) @ (12, 20)
Brand: jp2
Compatibility: ['jp2 ']
JP2 Header Box (jp2h) @ (32, 45)
Image Header Box (ihdr) @ (40, 22)
Size: [800 480 3]
Bitdepth: 8
Signed: False
Compression: wavelet
Colorspace Unknown: False
Colour Specification Box (colr) @ (62, 15)
Method: enumerated colorspace
Precedence: 0
Colorspace: sRGB
Contiguous Codestream Box (jp2c) @ (77, 115228)
UUID Box (uuid) @ (115305, 671)
UUID: be7acfcb-97a9-42e8-9c71-999491e3afac (XMP)
UUID Data:
<ns0:xmpmeta xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:ns0="adobe:ns:meta/" xmlns:ns2="http://ns.adobe.com/tiff/1.0/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" ns0:xmptk="Exempi + XMP Core 5.1.2">
<rdf:RDF>
<rdf:Description rdf:about="">
<ns2:ImageWidth>480</ns2:ImageWidth>
<ns2:ImageHeight>800</ns2:ImageHeight>
<ns2:BitsPerSample>3</ns2:BitsPerSample>
</rdf:Description>
<rdf:Description rdf:about="">
<dc:Title>Stürm und Drang</dc:Title>
<dc:Creator>Glymur</dc:Creator>
</rdf:Description>
</rdf:RDF>
</ns0:xmpmeta>