1. Content of folders of this TUB-web site with many colour figures

For the new ISO-CIE-trend to a device independent and elementary visual RGB*-colour space for printers and displays, see
IE in English or IG in German or
JE in English or JG in German or
KE in English or KG in German or
LE in English or LG in German for eight display reflections
OE in English or OG in German for eight display reflections and ISO/IEC and DIN-test charts

The following web pages show real and intended CIELAB data and CIELAB colour differences,
real rgb/cmyk and corrected rgb data and/or a constant rgb->cmyk transfer to reach the intended CIELAB data.
The device and elementary hue output according to CIE R1-47 is intended for the devices:
- standard sRGB with RGB output,
- standard offset with CMYK output (4 colours with only Black K for grey output),
- standard offset with CMY0 output (always only 3 colours CMY for output),
- a PostScript laser printer with CMYK output (4 colours with only Black K for grey output).

2. New trend in image technology to a device independent visual RGB*colour space

New developments lead to a visual RGB* colour space, which includes many visual properties of colour vision, and is device independent contrary to all other device dependent RGB colour spaces.

For the Information technology the development of a visual RGB colour space, which is here called RGB* (star) colour space, has been required in resolutions of ISO/TC159/SC 4/WG 2 "Ergonomics ­ Visual display requirements", and of ISO/IEC SC28 "Office Equipment" in resolutions to the CIE Division 1 "Vision and Colour" and the CIE Division 8 "Image Technology".

The two CIE-Reportership Reports:
CIE R1-47:2009: Hue Angles of Elementary Colours
CIE R1-57:2013: Border between Blackish and Luminous Colours
are important steps of this development.
For free download see the two archive URLs of the two former public papers:
Thorstein Seim (2009), Reportership Report CIE R1-47, Hue angles of elementary colours, see (35 pages),
http://web.archive.org/web/20160304130704/http://files.cie.co.at/526.pdf
Thorstein Seim (2013), Reportership Report CIE R1-57, Border between Blackish and Luminous Colours, see (23 pages),
http://web.archive.org/web/20150413002133/http://files.cie.co.at/716_CIE%20R1-57%20Report%20Jul-13%20v.2.pdf

In the report CIE R1-47 the CIELAB hue angles hab = 26, 92, 162, and 272 degree, which agree to the hue angles of the CIE-test colours no 9 to 12 according to the CIE-Publication 13.3, are recommended as hue angles for the elementary colours Red, Yellow, Green, and Blue RJGB. These hue angles are used in DIN 33872-1 to 6 for the input and output on monitors, displays, and printers.

In the report CIE R1-57 the colours of the colour attribute blackness n*=0 are described. The CIE tristimulues value Y changes depending on chromaticity. Such colours are used in the colour systems of Ostwald, DIN 6164, NCS, and sRGB.

The CIE-Reportership Report
CIE R8-09:2015 Output Linearization Methods for Displays and Printers with K. Richter as CIE reporter includes the present state of this development. The CIE goal is described by the following sentence:
"Make a report on proposals for the application of output linearization methods. The output may cover the device and elementary hue output of displays and printers." There is a free download of CIE R8-09:2015 (61 pages) only for about 150 members of CIE Division 8 "Image Technology" from the CIE CollTool server. Aproximately the same technical content is available in a paper of K. Richter 2016, Output linearization method OLM16 for displays, printers, and offset print (61 pages, 1,3 MB, format A4), with revised links in 2019, see OUTLIN16_01.PDF.

For newer pages with further basic information and examples, see
UE, VE, WE, XE, YE in english or
UG, VG, WG, XG, YG in german

The last two pages include data about the performance between the visual evaluation and the calculation of colour differences for five formulae CIELAB, CMC, CIE94, CIEDE2000, and LABJND.

3. German standards DIN 33872-1 to 6:2010

The German standards DIN 33872-1 to 6:2010-12 on Image Technology define many colour output properties for the digital DIN-test charts on monitors, displays, and printers, see
http://farbe.li.tu-berlin.de/A/33872E.html

The main topic of this web site are methods to fulfill the criteria of DIN 33872 for any colour device.
In general there is only one solution, which technically may be described by a transformation rgb to rgb' for monitors and printers and additionally by a transformation rgb to cmyk' for printers. If the manufactures have linearized their devices in CIELAB, for example according to ISO/IEC TR 15797 (which happens more and more rarely), then it is valid rgb' = rgb for any colour.

If this is not the case then colour measurement and output linearization in CIELAB is necessary for the different colour devices, for example a colour laser and a photo printer.

Here the colour test chart output with 1080 digital colours including a 9x9x9 rgb colour grid are used in digital files to measure the start and the linearized output in CIELAB, see for example the test chart (4 pages, 400 KB)
IE00L0NP.PDF
The results are for example shown in the device colour space (8 pages, 3,9 MB)
GE87L0NP.PDF
or in the elementary colour space (8 pages, 3,9 MB).
HE87L0NP.PDF
The even pages show the start output and the uneven pages the linearized photo printer output in four opponent hue planes, for example R-G, R25J-G25B, R50J-G50B, R75J-G75B.

4. Relative Elementary Colour System (RECS) as reference

A reference colour output is available in standard offset printing on standard offset paper. This colour atlas with about 2000 colour samples is called the Relative Elementary Colour System (RECS), see (1 page, 100 kByte)
RECS08.PDF

The tables rgb ­ rgb' or rgb ­ cmyk' for the linearized output in CIELAB are calculated (see FP-Files). Different efficient methods are presently discussed to apply these tables for any output on any computer operating system.

With the linearization method of this web site it is in general possible to produce both an efficient colour coding and visual output on monitors and printers and additionally an efficient material output for printers (use of only the black colorant N to print the achromatic colours and not the overprint of CMY).

For any colour device it is in general possible to fullfill all criteria of DIN 33872. If the elementary output is used as standard according to user wishes then the hue output is equal compared to the reference output of the RECS colour atlas for all colour devices. The visual assessment of the output of the 1080 colours is often possible without a reference output and to a high degree independent of the illumination (for example for the CIE illuminations D65, D50, iD65 or iD50)

For many outputs in the device colour space, see
GE or PE91 in English or GG or PG91 in German

For many outputs in the elementary colour space, see
HE or PE92 in English or HG or PG92 in German

5. Colour output on Displays for 8 luminance reflections according to ISO 9241-306:2008; new Annex E

For the device colour output with the device reflection and 3 luminance reflections Lr=0, 2,5, and 40% according to ISO 9241-306:2008 in the CIELAB (a*, b*) chroma diagram, see (1 page, 100 kByte)
KE40L0NP.PDF

The display reflection 40% may occur for example in a presentation room, if the luminance of the LCD projector and daylight is equal on the display.

A new Annex E of ISO 9241-306 is under discussion in ISO TC 159/SC4/WG2 Visual Display Requirements and includes now a chromatic test chart for eight luminance reflections between Lr=0,3 and 40% of the display output.

For the chromatic standard ISO/IEC-test chart which is intended for a linearized output at work places, see (3 pages, 400 KB)
OE58/OE58D0NP.PDF.
Form A with questions about the output properties are on page 2 and the input-output relationship for Lr=0,3% (dark room) is on page 3.

For the chromatic ISO/IEC-test chart, which simulates the output at work places for eight luminance reflections, see (24 pages, 14 MB)
OE58/OE58D1PX.PDF.
At any work place usually only one output of the pages 1, 4, 7, ..., 22 gives an equally spaced output for all the 16 step colour series and in addition the best output for the ISO/IEC-image according to ISO/IEC 15775.

Instead of the device colour output often the elementary colour output is required with equally spaced colour series between the colours RJGB and Black N, and White W. This supports the ISO-CIE-Trend to a visual RGB colour space