| 摘要 |
A JPEG picture composite method, and a method and apparatus for superimposing OSD information. The composite method comprises: performing entropy decoding, AC/DC coefficient decoding, inverse DC prediction and inverse quantization on the JPEG bit data streams of a first picture and a second picture; then performing DCT coefficient synthesis in an order of JPEG raster scanning according to the picture splicing mode; and performing quantization, DC prediction, AC/DC coefficient coding and entropy coding to form the JPEG bit data stream of a composite picture. As for the superimposed OSD information, only an area requiring the superimposition of OSD information undergoes IDCT change, a DCT coefficient is obtained by means of DCT transform after the OSD information is superimposed in a YUV plane, and this DCT coefficient as well as the DCT coefficient of a non-superimposed area are subject to DCT coefficient synthesis. The method and apparatus have no need of conducting IDCT transform and DCT transform on the entire JPEG picture, calculation amount is less and composite efficiency is high. |
