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For detailed information about the format support and control parameters, see JPEG 2000 in the File Formats section.
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The ImageGear JPEG 2000 Component allows you to extensively utilize the functionality of the JPEG 2000 Standard (ISO/IEC 15444-1). It provides the following advantages:
- The ability to read and write raw JPEG 2000 code stream files.
- The ability to read and write JP2 format files.
- The ability to update JP2 format file metadata without image pixel data decoding and encoding.
- The ability to convert between JP2 file format and raw JPEG 2000 codestream without image pixel data decoding and encoding.
- Excellent image quality at high compression rates. A major difference between JPEG 2000 and the well known JPEG (Joint Photographic Experts Group) technique is the use of the analyzing method. While JPEG uses the Discrete Cosine Transform, JPEG 2000 uses a special Discrete Wavelet Transform, which results in improved image quality. The Discrete Wavelet Analysis is performed over the whole image without partitioning it into many different tiles. The reconstructed image does not contain blocking artifacts corresponding to these initial tiles even at high compression rates. See the "Discrete Wavelet Transform (DWT)" section of JPEG 2000.
- The choice of lossless and lossy image compression. The analyzing wavelet filter operation allows a lossless compression at low compression rates and a lossy compression at higher rates. The lossless compression provides lower compression rates than even the maximal quality lossy compression. However, JPEG 2000 lossless compression outperforms comparable lossless image compression techniques like LZW and TIFF. See Saving JPEG 2000 and JPX Images in Lossless Mode.
- User controlled output loss compression rate. The image to be stored may be compressed to either a predetermined rate or to achieve a desired quality. If set for a predetermined compression rate the size of the resulting JPEG 2000 code stream will meet the rate exactly. While using other compression techniques, the size of a compressed file depends on the image contents and differs over a wide range. In addition to the overall compression rate, the JPEG 2000 Component allows you to set a different number of quality layers when writing an image, specifying the compression rate for each layer. See the RATE_BYTES and QUALITY_LAYERS control parameters in the JPEG 2000 File Format section.
- Support of different pixel formats. The JPEG 2000 Component supports palette-based, grayscale, and true color images, and a broad range of bit depths. See JPEG 2000 in the File Formats section for a detailed list of supported pixel formats.
- User controlled opacity and transparency information (alpha channel transparency). Regular and “Premultiplied” Alpha channels are supported. In a more common case when all color channels use the same alpha channel, ImageGear allows this alpha channel to be used for display, image processing, and saving to other formats. In cases of more complex Alpha channel configurations, ImageGear allows accessing these Alpha channels using its Extra channel functionality, so that the application may process them appropriately. See the "AlphaMapping" metadata tag description in the JPEG 2000 Component Metadata section.
- Support of Extra channels (additional unspecified channels).
- Support of restricted ICC profiles.
- User controlled reading and writing of JPEG 2000 format metadata (XML and IPR). XML and IPR metadata does not affect the decoding or visual appearance of the image itself. See the JPEG 2000 Component Metadata section.
- Preview generation and scaled image reconstruction based on embedded coding techniques: The resolution progression feature of the compressed JPEG 2000 data is best suited to perform a scaled reconstruction. The reconstruction process can be interrupted at any time and the partly processed data contains information of the full-size image. The reconstructed image appears in the appropriate quality corresponding to the processed amount of image data. If the image is reconstructed only for preview purposes, the best quality is not necessary because it is displayed at a fraction of the original image size. Using ImageGear JPEG2K component the quality and size of the reconstructed image can be scaled. This reconstructed image may be shown clearly because critical image information is located at the beginning of the compressed file, and remaining data follows in the order of detail. See the DISCARD_LEVELS, VIEW_WIDTH, VIEW_HEIGHT, and PROGRESSION_ORDERS control parameters in the JPEG 2000 File Format section.
JPEG 2000 image compression is suited well for sensitive image compressions because of the lossless feature, or for its excellent image quality at high compression rates for uses such as transmission in low bandwidth applications.
As soon as the JPEG 2000 Component is attached ImageGear Core, you can access the JPEG 2000 Format Filter functionality using the Core API, in the same way as you would access functionality of other file format filters. Use JPEG 2000 filter control parameters to control the features that are specific to the JPEG 2000 format. See "Using File Filter Control Parameters" in Loading and Saving for information about how to work with the filter control parameters API. See JPEG 2000 in the File Formats section for a list of control parameters available for the JPEG 2000 format.
