| 摘要 |
<p>PROBLEM TO BE SOLVED: To facilitate the format conversion processing and to increase the format converting speed by applying the band limit processing to the discrete cosine coefficient data to decrease the high band components and also applying the interpolation processing to the decoded image data to change coincidence with the number of pixels of a frame image to be decoded. SOLUTION: When the coded data D1 are decoded, the band limit processing is applied to DCT coefficient data D5 outputted from an inverse quantization part 4, via a masking part 21 to decrease the high band components. Meanwhile, the horizontal and vertical interpolation processes are applied to the image data outputted from an addition circuit 6 via an interpolation filter part 23 to convert the image data into an image format. Thus, the band limit processing is performed in a DCT coefficient step to eliminate the need for preparing both horizontal and vertical band limit processing circuits independently of each other. Furthermore, the band limit processing is performed in a DCT coefficient step, where the quantity of data is reduced and before the inverse DCT decoding processing. As a result, the format converting speed is increased.</p> |
