Image processing method, image processing apparatus and data recording medium

Abstract

An image processing method for dividing a digital image signal into plural image signals corresponding to plural blocks constituting a single display screen, and performing block-by-block coding of the image signals of the respective blocks, comprises transforming an image signal of a coding target block to be subjected to coding into frequency components by frame-by-frame frequency transformation on a frame basis or field-by-field frequency transformation on a field basis; setting a processing order for coding the frequency components corresponding to the image signal of the coding target block, according as the image signal of the coding target block has been subjected to the frame-by-frame frequency transformation or the field-by-field frequency transformation; and successively coding the frequency components corresponding to the image signal of the coding target block according to the order which has been set. Therefore, in coding of an interlaced image or a specific progressive image in which frame DCT blocks and field DCT blocks coexist, a run length is increased, thereby improving coding efficiency.

Description

[0001]Notice: More than one reissue application has been filed for the reissue of U.S. Pat. No. 6,426,975. The resissue applications are Ser. No. 10 / 682,849, filed Oct. 10, 2003, now U.S. Reissue Pat. No. RE 39,318, and the present application, which is a divisional reissue of U.S. Pat. No. 6,426,975.FIELD OF THE INVENTION[0002]The present invention relates to image processing methods, image processing apparatuses, and data recording media and, more particularly, to image processing methods, image processing apparatuses, and data recording media in which, in variable-length coding of frequency components of an interlaced image signal, a sequence of the frequency components is adaptively rearranged, thereby improving coding efficiency.BACKGROUND OF THE INVENTION[0003]In recent years, discrete cosine transformation (DCT) has been widely utilized in image coding processing. In MPEG as a representative image coding method, an input image signal is divided correspondingly to plural recta...

AI Technical Summary

Benefits of technology

The present invention provides image processing methods and apparatuses that improve the efficiency of coding interlaced images and progressive images. These methods involve adaptively selecting the best scan for coding based on the frequency components of the image signals, resulting in a more efficient use of coding resources. Additionally, the invention provides data recording media in which these image processing methods are recorded. The technical effects of the invention include improved coding efficiency and accurate and efficient decoding of DCT coefficients.

Problems solved by technology

In addition, in a case where the efficiency of variable-length coding is degraded by predicting AC coefficients, no AC prediction may be carried out.

However, in interlaced image coding in which frame DCT blocks and field DCT blocks coexist, since a field DCT block and a frame DCT block have different distributions of DCT coefficients, coefficients of about the same size are not consecutive when the same scan changing method is used, so that the efficiency of variable-length coding is degraded.

Further, also in inter-frame predictive coding of an interlaced image in any of the conventional image processing apparatuses, the above-mentioned problem arises because macroblocks having different DCT types coexist.

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