1. Field of the Invention
The invention relates to a method of decoding (reproducing) a moving picture (image signals) which is compressed in a determined compression method and a moving picture reproducing device which performs the method. In particular, the invention relates to a method of decoding compressed moving picture at various decoding precision levels (resolutions) and reproducing the decoded moving picture and a moving picture reproducing device which performs the method.
2. Description of the Related Art
A conventional video signal coding technology is prescribed in a standard, such as MPEG (Moving Picture Experts Group: which is well known as an International Standard of a moving picture compressing method). Such a coding technology is used to reduce an amount of information of moving picture, and the compressed moving picture is used in communication and data accumulation.
A user instructs a PC (personal computer) to reproduce the compressed moving picture by using a GUI (Graphical User Interface) implemented in an Operating System running on the PC. In this event, the user may change a display size of the moving picture by using a pointing device such as a mouse.
The change of the display size of the moving picture is done by a graphic hardware, and is not related to a decoding process of the compressed moving picture. For example, even if the display size is reduced to fifty percent in a vertical and a horizontal direction, the decoding process is performed about all signals of the compressed moving picture. However, it is to be considered that detailed information (high frequency component) included in the decoded moving picture is lost due to the reduction of the display size.
Also, there are various display devices to display the decoded moving picture. In general, a single display device can display the image in a plurality of resolutions. Therefore, when the image is displayed in a low resolution or in a small display size, a size of the image may be reduced so as to match with the display size.
However, in the prior art, decoding process is performed about all signals of compressed moving picture, regardless of the display size. Thus, there is a problem that decoding process of high frequency components, which are not displayed after all, is performed even when the display size is smaller than an original display size of the moving picture.