[工学]多媒体 Chapter 5.ppt

Chapter 5Fundamental Concepts in Video;Chapter 5Fundamental Concepts in Video;Component video 名词解释;Most computer systems use Component Video, with separate signals for R, G, and B signals. For any color separation scheme, Component Video gives the best color reproduction since there is no crosstalk between the three channels. Component video, however, requires more bandwidth and good synchronization of the three components.;Composite Video--1 Signal;Composite Video;Composite Video;S-Video -- 2 Signals;The reason for placing luminance into its own part of the signal is that black-and-white information is most crucial for visual perception. In fact, humans are able to differentiate spatial resolution in grayscale images with a much higher acuity than for the color part of color images. As a result, we can send less accurate color information than must be sent for intensity information --we can only see fairly large blobs of color, so it makes sense to send less color detail.;5.2 Analog Video;interlaced 名词 原理;Fig. 5.1: Interlaced raster scan;Because of interlacing, the odd and even lines are displaced in time from each other -- generally not noticeable except when very fast action is taking place on screen, when blurring may occur.;Fig. 5.2: Interlaced scan produces two fields for each frame. (a) The video frame, (b) Field 1, (c) Field 2, (d) Difference of Fields;de-interlace 名词 原理; de-interlace; blacker-than-black ;Fig. 5.3 Electronic signal for one NTSC scan line.;NTSC Video;NTSC Video;Fig. 5.4: Video raster, including retrace and sync data;Color Model and Modulation of NTSC;This modulated chroma signal is also known as the color subcarrier The NTSC composite signal is a further composition of the luminance signal Y and the chroma signal as defined below: composite = Y +C = Y +I cos(Fsct) + Qsin(Fsct) (5:2);Fig. 5.5: Interleaving Y and C signals in the NTSC spectrum.;Decoding NTSC Signals;To extract I:;PAL Video;PAL Video;PAL Video;PAL Video;SECAM Video;SECAM Vid