Template: Infobox file format / Maintenance / Magic number is missing template: Infobox file format / Maintenance / missing site
JPEG 2000 ( ISO standard 15444 ) is a graphics format for raster graphics with image compression, such as PNG or GIF. However, JPEG2000 based on the discrete wavelet transform (DWT). As the well-known JPEG it is issued by the Joint Photographic Experts Group. JPEG 2000 allows for both lossless and lossy compression. The format is good compression rates for photo-like images can be achieved. The image files can take a number of metadata that facilitate the management and retrieval of images.
Advantages over JPEG
The JPEG 2000 over JPEG format offers several advantages:
- Better compression rate for a given quality (quality as defined by objective metrics or subjective tests)
- More than 8/12 bits available per channel.
- Images greater than 64000 × 64000 pixels possible.
- Certain image regions of interest can be compressed and decompressed in higher quality (ROI = Region of Interest)
- Up to 256 color channels. This allows different color schemes as RGB and CMYK in an image, as well as other ICC profiles.
- Far more flexible than JPEG - various Progressionsmodi, images can be optimized according to various objective quality features.
- Space for arbitrary metadata in the Extensible Markup Language ( XML format)
- Prescribed incremental, ie stepwise image structure ( in JPEG optional). Characterized the display in the lower quality is possible simply by using only a part of the original file without recalculation.
- JPEG 2000 supports alpha channels for the representation of transparency.
Disadvantages compared to JPEG
- Significantly higher computational effort ( problematic for digital cameras)
- Significant dependence of the quality of the implementation
- All extensions of JPEG 2000 file formats that go beyond the pure image data stream (such as formats of metadata, color space data ) are not royalty free. Even for the image data stream is guaranteed by the JPEG -2000 Consortium expressly not the freedom of possible license claims of third parties.
Stages of compression
- Dividing the image into sub-images
- Transformation of color space (if color image)
- A- Posteriori (post - compression ) rate - distortion
In the case of lossy compression, the biorthogonal Daubechies-9/7-Wavelettransformation used. The lossless compression uses the biorthogonal LeGall-5/3-Wavelettransformation.
The decompression takes place in the reverse order without corresponding rate distortion.
Penetration and support
This format is widely used at the present time, but especially in professional environments such as medical and Digital Cinema ( standardized by the Digital Cinema Initiatives ) are used. The main reason is probably that sufficient precursor JPEG to most users, and that less free encoding software is available through licensing claims. Even the more expensive hardware solutions (such as decoder chips in digital cameras) slow the spread for private users.
There are qualitative differences in different decoders, which become noticeable, especially at higher compression ratios.
A simple, free way of creating offer ImageMagick, GraphicsMagick or Exact Image, based on the JasPer Library. However, is supported only simple compression.
A consistent implementation of the JPEG standard in open-source software promise OpenJPEG project, as well as the CQJ2K library of "Digital Signal Processing Laboratory " of the University of Perugia.
The XnView program in the Windows version ( 1.96 ) supports saving without size limitation.
For Adobe Photoshop, there was from version 5 to CS3 an optional plug-in ( available on the CD -ROM, removed since CS4); third party: a free plugin from fnord software, a free plugin with comprehensive software libraries and browser plug-ins of LuraTechs or the free for non-commercial use Plugin by LEAD Technologies, Inc. Today, Adobe's support JPEG2000.
Corel Paint Shop Pro Photo supported in Version 8 natively read and write JPEG 2000, PhotoLine supports it, as do the versions SE Plus, Ai Studio, DC Pro Studio and HDR Studio of scanner and imaging software SilverFast from LaserSoft Imaging.
Some common programs such as Microsoft Paint, do not yet support the standard. JasPer has proven itself on POSIX-compliant systems as a free alternative.
Mozilla Firefox for Mac OS X displays JPEG 2000. So Firefox is independent in this respect, an add-on for JPEG 2000 support was written as part of the Summer of Code '07. This code was never added to the Firefox core. The integration of JPEG 2000 in the browser are still opposed implementation of technical and patent issues.
JPEG 2000 is integrated into the PDF format since version 1.5.
File format and code stream
As JPEG - 1 differs JPEG 2000 a so-called code stream and file format. While the code stream is sufficient to decode the samples of the image, additional meta- information, such as the resolution and the color space of the encoded image stored in the file format. For the file format of the ISO specifies the file extension. Jp2, for the code stream no file extension is provided, since the code stream is not intended as such to be saved directly to a file. However, the endings. Jpc. J2c or. J2k this are common.
By wavelet transform avoids JPEG 2000 as opposed to JPEG -1 annoying blocking artifacts at high compression. Instead, the images tend to blur artifacts and shadows on stark contrasts. JPEG 2000 is particularly suitable for large images, because when the wavelet filters advantages over the relatively small 8 × 8 blocks have larger blocks of the DCT of JPEG -1. For smaller images, depending on the image content, and JPEG -1 provide a quality advantage.
The JPEG 2000 standard is divided into 13 sub- standards, ranging from the basic standard ISO / IEC 15444-1:2000, specify various additions and extensions to other application areas. These include, for example:
The standardization of JPEG 2000 has now been completed, however, the ISO maintains the standard further and even fixes bugs or discussed further additions.
JPEG 2000 is still not very present in the market for home users, but there are some special applications, in which it is used intensively:
- The DICOM standard for medical data can accommodate JPEG 2000 images.
- The Digital Cinema Initiatives, an association of most major movie studios / rentals to, Motion JPEG 2000 uses as a standard for storage, distribution and presentation of 2K and 4K footage.
- Some broadcasters use Motion JPEG 2000 data reduced transmission of SD / HD footage in their networks.
- Some large archives use JPEG 2000 for long-term archiving of your documents.
- On the new passports of the Federal Republic of Germany, the passport photos in JPEG 2000 format are stored with an image size of 18 kB.
- The virtual world Second Life software uses JPEG 2000 for storing all graphics and textures.
- Some exposure services use JPEG 2000 for the transfer of photos.