JPEG2000 is a modern format for image and video data storage featuring high compression ratio. Based on wavelet transformation, it includes a number of innovations that extend video surveillance capabilities.
JPEG2000 compression format received the global standard status in 1999. It replaced the traditional JPEG format, which is based on discrete cosine transform. Compared to JPEG, JPEG2000 offers a higher compression ratio. A JPEG2000 video frame has higher resolution compared to a JPEG image of the same file size, proved by both visual estimations and VQM tests.
Due to the wavelet compression algorithm, JPEG2000 does not add a visible «grid» that makes images less realistic. This unlocks new data processing capabilities.
- An image from a PAL camera, 720x576 pixels
- JPEG2000-compressed image
- JPG-compressed image
Intraframe compression
The choice of compression method is an important feature of video surveillance systems. For quality and realistic look, the basic method used is intraframe compression where each frame is compressed independently of others. JPEG2000 was initially designed for compressing static images but it has the «motion JPEG2000» extension for compressing video data. Since the algorithm was initially designed for static image compression, JPEG2000 offers an advantage over algorithms with interframe compression. Unlike MPEG2, MPEG4, H.264 and other algorithms, JPEG2000 ensures equally high quality for all frames. This allows using JPEG2000-encoded records for forensic examination and automatic processing of archived data, ensuring optimal quality and low resource consumption.
Resolution scalability
The JPEG2000 image format keeps data for different resolutions in different blocks. This allows storing images in several resolutions in the same data stream. To obtain a video with low resolution you have to unpack only a part of archived data. The NetScale technology of VOCORD Tahion uses this specific feature of wavelet transformation and reduces the load on digital communication channels by sending only the part of data that contains the image with required resolution.
Frame rate scalability
Another option that reduces the size of transferred video data is removing some frames from the video stream, which can be easily done if intraframe compression is used. This feature, being a part of the NetScale technology, provides another advantage for VOCORD Tahion.
Processing video data without decompression
Decompression of compressed data requires significant computing resources. The block structure of JPEG2000 data allows automatic processing of archived data without prior full decompression, which saves computing resources.
Certified quality
JPEG2000 is a winning approach to video registration quality, featuring high level of detail for each video frame. The implementation of StreamLogic and JPEG2000 algorithms ensured the success of VOCORD system at the certification testing by the Ministry of the Interior of Russian Federation and resulted in their resolution on the applicability of video and audio materials recorded by VOCORD Avantpost for scene reconstruction, face identification, and forensic examinations.
