Research On Application Of Image Data Compression Technique In PDF

Portable Document Format (PDF) is the object to be studied in my paper, which is one of the electronic document formats. How to write image data to PDF is the focus of the study. Image data compression and its application in PDF are studied in-depth in the paper.At first, the characteristics and structure of PDF and approach to produce PDF are studied in detail.Secondly, focused on how to load image to application in the environment of Java, a class is realized, which can load any image by the same way. In addition, an approach to extract pixel value from loaded image is analyzed and the corresponding realization in Java is given.Then, with the topic of how to use image data compression in PDF, image data compression techniques are studied in the paper. Arithmetic of data compression or data encoding that used in several version of PDF is discussed. They include ASCII85,ASCIIHex and Joint Photographic Expert Group (JPEG) arithmetic which is composed of Run Length Encoding (RLE), Discrete Cosine Transform(DCT) and Huffman. In order to improve the efficiency and speed of compression, the AA&N method is used in the step of DCT and quantization which are two of the steps in the realization of JPEG. Adaptive Image Compression and Encoding (AICE) is proposed and used in the step of writing image data to PDF. It chooses fit arithmetic to process image data according to the type of image it recognized. A good result is obtained by imported AICE. Further, corresponding scheme to resolve the problems encountered in the process of writing image data to PDF is given.Finally, a test system integrated all above realization is introduced. Two experiment results show the efficiency of arithmetic we proposed.