星期一, 1月 01, 2007

[JPEG]4.1Elements specified in this Specification

天ㄚ...


我還以為我會被前面的名詞定義給淹沒...


還好boss跟我說可以從4.1開始看...


終於可以先skip guideline了....好感動...


 


唔...看來是我疏忽了...我還以為只有boss會看...


趕快把原文補上...
(~~)






There are three elements specified in this Specification:





a) An encoder is an embodiment of an encoding process. As shown in  Figure 1, an encoder takes as input digital source image data and table specifications, and by means of a specified set of procedures generates as output compressed image data.





b) A decoder is an embodiment of a decoding process. As shown in Figure 2, a decoder takes as input compressed image data and table specifications, and by means of a specified set of procedures generates as output digital reconstructed image data.





c) The interchange format, shown in Figure 3, is a compressed image data representation which includes all table specifications used in the encoding process. The interchange format is for exchange between


application environments.





Figures 1 and 2 illustrate the general case for which the continuous-tone source and reconstructed image data consist of multiple components. (A colour image consists of multiple components; a grayscale image consists only of a single component.) A significant portion of this Specification is concerned with how to handle multiple-component images in a flexible, application-independent way.





These figures are also meant to show that the same tables specified for an encoder to use to compress a particular image must be provided to a decoder to reconstruct that image. However, this Specification does not specify how applications should associate tables with compressed image data, nor how they should represent source image data generally within their specific environments.





Consequently, this Specification also specifies the interchange format shown in Figure 3, in which table specifications are included within compressed image data. An image compressed with a specified encoding process within one application environment, A, is passed to a different environment, B, by means of the interchange format.


The interchange format does not specify a complete coded image representation. Application-dependent information,e.g. colour space, is outside the scope of this Specification.












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