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Psychophysikalische Experimente zur Ermittlung des visuellen Farbsehsystems, insbesondere Experimente über Farbempfindungsmerkmale Buntton und Buntheit in In- und Umfeldern verschiedener Farben und Leuchtdichte. Besondere Bedeutung für die Bereiche Farbfotografie, Farbfernsehen, Mehrfarbendruck, Bildschirmfarbgrafik.
Four ISO/IEC-test charts have been defined in ISO/IEC 15775 (1999) to specify image reproduction of
colour copiers. Corresponding test charts have been defined in DIN 33866-1 to 5 (in print) to specify
image reproduction of colour copiers, printers, scanners and monitors. All colours of all test charts are
defined in CIELAB coordinates. In applications the devices including software are used for test chart
input and output in the three different combinations "analog - analog" (copiers), "digital - analog"
(printers, monitors) and "analog - digital" (scanners, Photo-CD-systems).
This paper uses mainly ISO/IEC-test colours of a 16 step grey scale (defined by olv*-coordinates
according to the standard) in the original scene to calibrate the variable (photographic and Photo-CD)
analog-digital process. The relative digital olv*-input data and the digital olv*'-output data are used to
get approximately the same digital output (image file) independent of exposure (e. g. between -1 stop
under to +2 stop over exposure for slide or negative film) and other variables, e. g. the digitizing Photo-
CD-process. This "direct" colour management method adds a new method compared to the ICC colour
management method which fails to handle variable processes and can not manage the variable data of
original scenes taken by the photographic process.
For colorimetric colour management and
communication 8bit colour codes in perceptive
space (*colour space) are described. Two Standard
Gamut Colour codes for Printing (PR) and Television
(TV) and one universal Wide Gamut Colour code
(WGcode) which includes all real colours of both PR
and TV. There are reverse transformations between
the two different SGcodes of PR and TV, the
universal WGcode and the CIELAB colour
coordinates. The SGcodes and the WGcode are
compatible with CIELAB, ISO/IEC 15775 and DIS
ISO/IEC 19839-1 to 4 which specify image
reproduction properties of colour copiers, printers,
scanners and monitors. These standards correspond
to DIN 33866-1 to 5.
The SGcodes and the WGcode can be calculated for
all colours of the four ISO/IEC-test charts which are
all defined in CIELAB coordinates. Main colour
series are equally spaced in CIELAB colour space
both in lightness L* and chroma C*. Up to now there
are productions of DIN (German Standard Institute)
and JBMA (Japan Business Machine Makers
Association) according to ISO/IEC 15775 which can
be used for all applications.
The 8bit SGcode of television is similar compared to
the nonlinear 8bit code of the sRGB colour space
defined in IEC 61966-2-1:1999-10 which is
incompatible to CIELAB and ISO/IEC 15775.
The four analog ISO/IEC-test charts in reflectance mode according to ISO/IEC 15775 are designed for
the test of colour copiers. The test charts include many image elements. e. g. Siemens-stars, Landoltrings
and 16 step equally spaced colour scales according to CIELAB. Most important for image
technology is the ISO/IEC pictorial image B1 which includes a 16 step grey scale and 16 CIE-test
colours.This image comes in 5 resolutions between 128 x 192, 256 x 384, and 2048 x 3096 pixels. For
analog production the digital ISO/IEC-test charts are described in ISO/IEC 15775.
Some applications of the digital and analog ISO/IEC-test charts for printers, monitors and scanners will
be discussed. Recently three methods to optimize the ISO/IEC-test chart output have been developed.
Between the digital input values and the CIELAB colour difference of the 16 step colour series a linear
relationship is produced. This linear property allows new and very simple colour management methods.
The application of these methods for the production of the reference ISO/IEC-test charts and for colour
management of slide and negative film images as function of exposure is shown.