Image processing device and image processing method

Abstract

It is possible to suppress image quality degradation caused by encoding. The present invention multiplies a decoding rescaling factor (RFr) which may be used during decoding only by a conversion matrix (D) as a scale fluctuation so as to calculate rescaling factors (RF) as division factors and calculate a sum (sigma Y) of evaluation values (Y) based on a remainder (r) when an elements in the DCT coefficient is divided by the rescaling factors (RF), for each of detection unit. Furthermore, the present invention compares relationships between the rescaling factors (RF) and the sum (sigma) of evaluation values (Y). The rescaling factor (RF) at which the sum (sigma) of evaluation values (Y) is minimum is used to detect a quantization factor used upon the previous encoding of the input image data.

Description

technical field [0001] The present invention relates to an encoding device that detects things such as quantization matrices or quantization parameters used in previous encoding processing in predetermined units, for example. Background technique [0002] Conventionally, when exchanging video data between television broadcasting stations or duplicating video data using multiple video tape recorders (VTR devices), video data encoded using MPEG (Moving Picture Experts Group) was first decoded, and then It encodes. This is why it is necessary to sequentially connect an encoder and a decoder in series. [0003] Also, such a tandem system repeats encoding and decoding, so that the quality of video data is degraded accordingly. To prevent this, a so-called "backsearch" can be applied. [0004] Here, the "backward search" calculates the quantization step size of the minimum value as an appropriate quantization step size based on the following characteristics: If the quantization...

AI Technical Summary

Problems solved by technology

[0009] However, even if AVC Intra uses the same detection technique as MPEG to solve the above ripping problem, it may not work: the ripping causes the degradation of video data quality because its encoding system is different, and the accuracy of the backward search thus lowered

Images