STYDY ON LINE IMAGE TRANSMISSION OF HIGH-RESOLUTION PRINTED IMAGE PROCESSING SYSTEM

目前已经提出了多种数字图像编码方法，其中JPEG编码方法最为有效。JPEG方法已被采纳为图像压缩的国际标准。然而，这种方法也存在一些不足之处。例如，DCT(离散余弦变换)的块大小固定为8*8。对于高分辨率的数字图像，一次处理的像素很多。因此，研究如何有效地压缩一幅图像是非常重要的。我们对这一问题进行了研究，并找到了一种非常有希望的高分辨率数字图像压缩方法。基本思想是根据局部图像的特性改变DCT的块大小。在这种情况下，块大小与图像属性之间的关系是非常重要的。我们发现了一个用于确定块大小的非常有用的索引。这被称为活动指数，很容易获得该指数的值。基于这种思想，我们尝试了许多种高分辨率图像的模拟，称为SCID(Standard Co；或Image Data)，它将被国际上采用的高分辨率数字彩色图像。实验结果表明，该方法对于高分辨率印刷图像的在线传输是非常有效的。

Tehre have been proposed many kinds of digital image coding methds, and the JPEG method seems to most powerful. The JPEG method has already been adopted as an international standard for image compression. However, there are some shortcomings in this method. For example, the block size for DCT (Discrete Cosine Transform) is fixed to be 8*8. For high-resolution digital images, there are many pixels to be processed at a time. Therefore, it is very important to investigate how to compress an image efficiency.We have studied this problem, and found a very hopeful method foa compressing high-resolution digital images. The basic idea to to vary the block size for DCT according to the properties of local images. In this case, the relation between the block size and the properties of images are very important. We found a very useful index for determining the block size. This is called an activity index and it is very easy to obtain the value of the index. Based on this idea, we tried many kings of simulations for high-resolution images called SCID (Standard Co ; or Image Data) which will be adopted an international high-resolution digital color images. It was found that the proposed method is very effective for online transmission of high-resolution printed images.