530
©
4-color
printing
gamut
O 700 mm
Figure 4.--C.I.E. diagram showing printing color gamut limitations
compared to electronic and visual color displays (adapted from
Williamson, 1983).
Film images of each band are photomechanically mosaicked (fig. 5).. Each
film-mosaicked band is exposed through a halftone screen to produce half-
tone film negatives for printing. Image film separates are punch regis-
tered with line/lettering film separates. A color proof is prepared as a
quality control guide for printing.
ADJUST CONTROL
AND PLOT CONTROL
BASE SHEET AT
FINAL SCALE
LBR FILM PAPER PRINTS 7.5 QUAD TRANSFER
FOR MARKING CONTROL FOR CONTROL CONTROL TO BAND
SELECTION 5 IMAGES AND MEASURE
(M) 3 >
COLOR PHOTOGRAPHIC
HALFTONE PROOF
IMAGE OF EACH EACH BAND FILM IMAGE SEPARATION
BAND ENLARED TO MOSAICKED REGISTERED TO LETTER/
FINAL SCALE AND HALFTONED LINE SEPARATION
Figure 5.--Photomechanical mosaic procedure (Warren, 1980).
Graphic Arts Electronic Scanning Procedures
Electronic scanning and digital enlargement of Landsat imagery results in
significantly improved quality compared to photographic processing. The
sensitometric conversion from photographic to lithographic reproduction,
enlargement in the x and y dimensions, and generation of the halftone dot
structure can be precisely controlled with an electronic scanner. Landsat
multispectral scanner (MSS) halftone separates can be produced at scales
as large as 1:250,000. The same procedures apply to the use of thematic
mapper (TM) imagery for electronic scanning and production of halftone
image separates at scales as large as 1:100,000.
212
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