MPEG Handbook: MPEG-1, MPEG-2, MPEG-4
The clarity of explanation and depth of technical detail combine to make this book an essential and definitive reference work.
TABLE OF CONTENTS MPEG Handbook: MPEG-1, MPEG-2, MPEG-4
Chapter 5: MPEG video compression
In this chapter the principles of video compression are explored, leading to descriptions of MPEG-1, MPEG-2 and MPEG-4. MPEG-1 supports only progressively scanned images, whereas MPEG-2 and MPEG-4 support both progressive and interlaced scan. MPEG uses the term picture to mean a full-screen image of any kind at one point on the time axis. This could be a field or a frame in interlaced systems but only a frame in noninterlaced systems. The terms field and frame will be used only when the distinction is important. MPEG-4 introduces object coding which can handle entities that may not fill the screen. In MPEG-4 the picture becomes a plane in which one or more video objects can be displayed, hence the term video object plane (VOP).
5.1 The eye
All imaging signals ultimately excite some response in the eye and the viewer can only describe the result subjectively. Familiarity with the functioning and limitations of the eye is essential to an understanding of image compression. The simple representation of Figure 5.1 shows that the eyeball is nearly spherical and is swivelled by muscles. The space between the cornea and the lens is filled with transparent fluid known as aqueous humour. The remainder of the eyeball is filled with a transparent jelly known as vitreous humour. Light enters the cornea, and the amount of light admitted is controlled by the pupil in the iris. Light entering is involuntarily focused on the retina by the lens in a process called visual accommodation
Copyright John Watkinson 2001 under license agreement with Books24x7
