2.2 - PRE-PROCESSING 
Introduction 
The Digital Processing Section is equipped with high density digital 
recorders identical to those at the DAF for play-back of data, three 
mini-computer based processing systems called the Bulk Processing System 
(BPS), the Precision Processing System (PPS) and the Development 
Processing System (DPS), four large disk storage systems, image writers, 
digital magnetic tape units and other standard peripherals. 
Four levels of processing are provided, the first three being performed by 
the BPS and the fourth by the PPS. These are: 
(a) reduced resolution imagery for cataloguing; 
(b) quick-look imagery; 
(c) bulk processing; 
(d) precision processing. 
Resolution Reduction 
On receipt of the high density digital tapes from the DAF, and prior to 
storage in the archive area, the data are played back onto computer disk 
file at reduced resolution. The data base containing listings of 
previously acquired scenes is updated and the images of every scene are 
examined on a colour TV style monitor for cloud cover and quality. This 
information is entered manually into the data base. The data base is read 
out to magnetic tape at monthly intervals (approx. two satellite coverage 
cycles) for subsequent production of a microfiche Data Catalogue. At the 
end of each satellite coverage cycle the disk file is written out onto 
colour negatives in the standard "times 24" microfiche format in the form 
of a complete set of micro-images of all scenes acquired. 
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