What is JPEG2000Robert HanUniversity of Wisconsin – Madison, College of EngineeringECE533 Final Project report1. IntroductionIn the digital image processing area, there are many different methods to compress images. Each compression method has different aspects and different characteristics. Among those methods, the compression standard developed by Joint Photographic Expert Group (JPEG) is currently the most widely used in many applications such as web applications. It is because that JPEG compression method can compress large amount of image data into relatively small amount of data size. About ten years later when JPEG image standard was developed, the new compression standard for image compression was developed in year 2000 and it was named JPEG2000. JPEG2000 is new image compression standard from JPEG and it adapts different algorithm from previous JPEG standard. With this new algorithm, JPEG2000 can perform much improved image compression with higher quality. However, JPEG2000 is not yet widely used in both commercial and non-commercial applications and most of general image application users do not know about this new image compression standard.Therefore, in this report, I will explore features and characteristics of JPEG2000 compression standard. First, I will explain the basic features of JPEG2000 image standard and make technical comparisons between JPEG2000 and JPEG technology. And introduce the Kakadu software which is developed to implement JPEG2000 images. And implement some JPEG2000 image samples with the Kakadu software and demonstrate results. Finally, I will perform the actual experiments withJPEG and JPEG2000 image and determine how JPEG2000 is improved over previous JPEG standard. 2. Background information of JPEG2000In digital image processing area, there was a need for a standard image compression method to enable interoperation among applications and equipments from different manufacturer. Therefore, the Joint Photographic Expert group (JPEG) was established with specialists from CCITT and ISO, and developed the first international digital image compression standard for continuous-tone images in late 1980s. Currently, JPEG images are the most widely used compressed image. In year 2000, about ten years after the JPEG standard was developed, the Joint photographic expert group developed new standard for JPEG image with different algorithm and this standard was named JPEG2000.JPEG2000 is a new image-encoding standard that provides a feature set vital to many high-end and emerging imaging applications. JPEG2000 provides high compression with image quality superior to all existing standard encoding techniques. This high compression and quality performance is due to the adaptation of wavelet transforms. Wavelet transforms are mathematical formulas that represent complex structures in the image, thereby compressing an extremely large amount of image datainto a relatively small amount of compressed data. This compression technique allowsapplications to save compressed images with higher compression ratio and better image quality as compared to any other software currently in production. And due to the wavelet based compression algorithm, JPEG2000 image can store the image data in a hierarchical format which contains several stored resolutions of the image in the 2same file without duplication. For this reason, a compressed with JPEG2000 standard image can then be sent to a device in the resolution that best fits without additional storage overhead. And the file structure of the image becomes very flexible, so that it can be used for a variety of applications such as internet images, digital photography, medical images, and wireless images. However, JPEG2000 images are not yet currently widely used in current commercial or non-commercial applications. Figure 1. JPEG2000 compression algorithmAlthough JPEG and JPEG2000 standard adapt different algorithm for image data compression, they share same basic architecture of standard. As shown in figure 2, source image data is quantized after the forward transform. And after the quantization, the data set is encoded through entropy encoding and transformed in to compressed image data. Figure 2. Basic Architecture of standard for JPEG/JPEG2000 image compressionThis basic structure is applicable to both discrete cosine transform for JPEG standard and discrete wavelet transform for JPEG2000 standard. 3. The KAKADU software Entropy EncodingSource image dataForward TransformQuantizationCompressed image data3The Kakadu software is a complete implementation of the JPEG2000 standard, Part 1. This new image compression standard is substantially more complex than the existing JPEG standard, both from a computational and a conceptual perspective. The Kakadu software also provides a comprehensive implementation for several of the most useful features from Part 2 of the JPEG2000 standard, including general multi-component transforms and arbitrary wavelet transform kernels.The Kakadu software framework provides a solid foundation for a range of commercial and non-commercial applications. The objective of Kakadu software is to encourage the widespread adoption of JPEG2000 image standard by making a consistent and efficient implementation of the standard widely available for both academic and commercial applications. The Kakadu software has been written specifically with a variety of different types of applications in mind. These include:Image and volume compressionImage and volume decompression/renderingTrans-coding between related representationsInteractive rendering applicationsClient-server applicationsDigital Cinema applicationsFor the experimental purpose, I actually performed implementations of JPEG2000 images with some basic functions of the Kakadu software and demonstrated results in this report. 4Figure 3. Basic figure of the Kakadu software4. Kakadu implementation examplesJPEG2000 image may contain multiple embedded image structure, which form the foundation of quality progressive remote image browsing. By default, local files are opened at maximum quality in the Kakadu software. With the Kakadu software, it is possible to reduce the number of layers of the image and to compare thevisual quality associated with each compressed quality layer. Figure 4. The Kakadu software implementation – Layer reducing examplesThe format of the original image is in the png format which stands for Portable Original
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