A modification of the codec for low-latency video data transmission systems based on a discrete wavelet transform is presented taking into account the option of changing the filtering direction of the samples from vertical and horizontal to diagonal developed at the TiZV department of MTUCI, allowing to slightly reduce computational complexity by reducing the number of processed extrapolated elements at the edges of the image (or tile), simplify parallel processing of data, and also introduce an additional level of fault tolerance these transmission systems directly to the video codec by generating a pair of independent mutually complementary data streams. Particular attention is paid to the issues of data synchronization and fault tolerance of video information systems, in which, to obtain high spatial resolution, the image is divided into fragments with their subsequent separate decoding and playback. The features of image compression standards based on a discrete wavelet transform are considered. The concepts presented here are a suggestion for consideration by Working Group IV. ACR-NEMA Working Group IV is the group that is considering compression standards for medical images. The Digital Image Communications In Medicine (DICOM) standard is the interchange standard within which the compression is meant to be used. When the compression standard is available, it may be used in the interchange of medical images. In these areas there are less than one bit per pixel and multiple pixels must be coded together for the most effective compression.
To be really effective the coding must have an extension for the areas where there is little information, the low entropy extension. Huffman coding or the coding of the RICE algorithm are a beginning for the encoding. The compression realized depends on the similarity of close transform coefficients. The lapped orthogonal transforms groups the data according to the area where the data originated, while the wavelet transforms group the data by the frequency band of the image.
These transforms decompose the images in frequency in two different ways. Two preferred decompositions of the medical images are lapped orthogonal transforms and wavelet transforms.
IMAGE COMPRESSION STANDARDS SERIES
Related series of images as for CT, MR, or cardiology require inter-image processing as well as intra-image processing for effective compression. To have one or a very few compression algorithms that are effective across a broad range of image types is desirable. A medical imaging compression standard must be applicable across a large variety of image types from CT and MR to CR and ultrasound. New requirements for compression arise from the fact that the images will likely be viewed on a computer workstation, where the images may be manipulated in ways that would bring out the artifacts. The compression artifacts should not interfere with the viewing of the images for diagnosis. The requirements for compression for medical images center on diagnostic quality images after the restoration of the images. The older algorithms, JPEG and MPEG in particular, are generally not adequate for high quality compression of medical images. After clinicians become acquainted with the quality of the images using some of the newer algorithms, they accept the idea of lossy compression. Compression saves communication bandwidth and reduces the size of the stored images. Cost effective telemedicine and storage create a need for medical image compression.
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