Images in ISO/IEC-test charts which show basic problems of colour reproduction and produce equal output for corresponding colours defined in CIELAB related device spaces
暂无分享,去创建一个
Corresponding colours of the olv* and cmy0* colour spaces (described by the PS image operators "4 colorimage, 3
colorimage and image" and described by the PS vector graphic operators "setcmykcolor, setrgbcolor and setgray")
show in a lot of cases an equal output as required by users and colorimetry. For many software - hardware combinations
the colours defined in the olv* and cmy0* colour spaces appear very different (about 15 CIELAB) in the
output. An example is the software Adobe Reader which produces a brownish output on the monitor for the greys
defined in the cmy0* colour space compared to the achromatic output for greys defined in the olv* colour space.
An ISO/IEC-test chart file uses the 6 different PS operators on one page. This test chart is used for a system test
(combinations of hardware and software) of the device colour output. For this test the 16 step colour scales of Fig.
B4 and D4 of the ISO/IEC-test chart according to ISO/IEC 15775 are used. If unexpected result occur then there are
methods to correct the output. e. g. by the MTL code (Measurement, Transfer and Linearisation).
A local, global or external transfer is used to make the output of raw scan olv*' image data of slide and negative film
very similar. A large variation of exposure has no influence on the output. For slide film this exposure range is
between about -0,5 stops (under exposure) and +1,0 stops (over exposure). For negative film the exposure range is
between about -1,0 stops (under exposure) and +3,0 stops (over exposure). The output appears the same for a local
and external transfer. All the different exposures of two film materials are shown on one page. The global transfer is
applied to an image of the flower motif (Fig. B1 and D1 of ISO/IEC-test chart according to ISO/IEC 15775).