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THE BELL SYSTEM TECHNICAL JOURNAL, JULY 1952 



values, namely aSi.o , aSo.i and >Si.i . The predicted signal is given by 



Sp = 01,0 4" So^i — *Si,i . 

 The filter characteristic is given by 



F(w) = 4 sin — sin -— e ^ ^ ^ 



The peak error ampUtude for "Planar" prediction can be four times 

 that of the input signal. 



"Planar" prediction has several good characteristics. For example, 

 if S>\,\ and »Si,o were white and >So.i black, then *So,o would be predicted 

 to be black. Thus a change horizontally from white to black would 

 produce no errors. Similary, if *Si,i and <So,i were white and aSi.o black, 

 then *So,o would be predicted to be black. This indicates that a change 

 vertically from white to black would be predicted correctly. In this 

 manner, all vertical and horizontal contours in a picture are deleted. This 

 philosophy can be extended to include other directions as well. 



"Circular" prediction, illustrated in Fig. 9, is an extension of planar, 

 since it deletes horizontal, vertical and 52° contours as well. A total of 

 190.5 microseconds of delay is required, making the required equipment 

 more elaborate. Also, as more delay is required, more noise is added. 



» o— — o 



1,3 0,3 

 ^ 



> O O ^\ 



2,2 -1,2 ^"-y INTERLACED 

 ^" / FIELD 



/ 

 / 

 > O O ' 



2,1 -',1 ^ 



* o X 



1,0 0,0 



Sp = S)^o "" ^2^1 + ^2,2 ~ S)^3 + So,3 ~ S-i^a"*" S-i,t 



Fig. 9 — Past signal samples required for "circular prediction" — a type of 

 prediction which removes horizontal, vertical, and d=52° straight line picture 

 contours. 



