Four ISO/IEC- and DIN-test charts have been defined in ISO/IEC 15775:1999-12, DIS ISO/IEC 19839-1 to -4:2000-04, and DIN 33866-1 to 5:2000-08 to specify image reproduction of colour copiers, printers, scanners and monitors. The committees ISO/IEC JTC1/SC28 "Information technique, Office equipment" and the corresponding German committee have developed these key standards of information technology during the last four years.
New colorimetric technologies of BAM have been used to produce the first set of four DIN-test charts in offset printing (3600 dpi) which are in application for colour devices (for example copiers, printers, scanners and monitors). The first production of (Asian) ISO/IEC-test charts according to ISO/IEC 15775 have been produced in Japan by JBMA (Japan Business Machines Makers Association).In applications the devices including software are used for ISO/IEC-test chart input and output in three different combinations analog - analog (copiers), digital - analog (printers, monitors) and analog - digital (scanners, Photo-CD-systems).
The method of specifying image reproduction for colour copiers uses the device as a black box and compares mainly visually the input and output (reproduction) of the ISO/IEC-test charts by filling out ISO/IEC-forms depending on the ISO/IEC-test chart number. Transparent ISO/IEC-test charts on a flat area lamp serve as reference monitor. There is no way to calculate in advance this visual assessment for Siemens-stars, Landolt-rings, characters, line screens and other ISO/IEC-test chart elements in different sizes and colours. Using ISO/IEC-test charts for input and output is the only very practical way to specify image reproduction in offices.
Now ISO/IEC and DIN are looking for the most promising technologies to produce new ISO/IEC- and DIN-test charts in different modes (reflectance and transmission), on different materials (offset, photographic paper and film) and with different resolution. For production the digital ISO/IEC-test charts are defined in PostScript (PS), Portable Document File (PDF) and equivalent formats .
Only small colour differences of analog test charts compared to the colorimetric definitions in the International Standard ISO/IEC 15775 are intended. The digital ISO/IEC- and DIN-test charts for production and applications are available on the Internet and will produce for example an output on any printer or monitor. The digital ISO/IEC-test charts can be used by any manufacturer who decides to produce analog ISO/IEC-test charts. The different requirements of the produced ISO/IEC-test charts are defined in ISO/IEC 15775.
The first DFZ-BAM-workshop in Nov. 1999 on this topic has brought together the experts of ISO/IEC, DIN and BAM and manufacturers of the new ISO/IEC-test charts to look at the first production results. The specification of image reproduction both by visual assessment and measurement in comparison with the colorimetric definition within the International Standard ISO/IEC 15775 has allowed discussion and selection of the most promising (and stable and reproducible) methods for the next ISO/IEC-DIN-BAM-test chart productions in different modes, on different materials and in different resolutions
informations and registration:
Deutsches Farbenzentrum (DFZ), Bozener Strasse 11-12
D-10825 Berlin, Germany
Fon and Fax +49-30-854 63 61(same number, see the URL:) www.farbenzentrum.net
For the paper abstract and workshop exercises all related
to test charts see www.ps.bam.de/NEWSE.html
(see also forms for workshop registration, maps, and recommended hotels)
In a poster room are materials for the production of ISO/IEC-test charts. There are presentations of colour image reproduction devices (colour copiers, printers, monitors and scanners). Colour measuring instruments of leading manufacturers and the BAM staff will guide for the input and output of the DIN- and ISO/IEC-test charts and the comparison with the reference. Within the workshop and the exhibition it is intended to reproduce the test charts on ISO/IEC reference paper by new Input and Output Linearization methods (IL and OL).
Within the workshop the intention is to correct the digital input data of ISO/IEC-test charts - both by visual estimation and colorimetric measurement - to get the output on any colour reproduction device within visual tolerances identical and independent of hardware and software . Examples of colour scales and colour images will be produced and shown in the exhibition. Colour image reproduction devices and materials of the following companies are expected: Apple, Epson, Fuji, Oki, Osram, Tektronix, Xerox. (Registration and Information only by DFZ).
The new flat area lamp OSRAM PLANON D65 (10.000 cd/squaremeter) in size A4 and larger will be shown in the colour exhibition. With transparent film material on top this lamp represents the light colour mode of the ISO/IEC- and DIN-test charts and serves as analog reference monitor .
technologies within the BAM-conference room:
The BAM-conference room has capabilities for one overhead projection, double slide projection (2 times 4 m x 3 m), PC to video projections ((Mac and Windows, 4 m x 3 m), and 6 distributed microphones for questions and discussions. There are additional possibilities for the presentation of the ISO/IEC-test chart materials in a poster room.
Remark 1: During
the working sections a notebook, a video display and a black and
white printer and a colour printer are used. Digital standard
files are freely available on the Internet with many figures of
the digital ISO/IEC-test charts. A low cost ($500) colour measurement
equipment serves for the colour measurement technique. Participants
can use their own notebooks and the standard ISO/IEC-test chart
files (see www.ps.bam.de/DE.HTM) to optimize visually the output
on their notebooks and/or their printers.
Remark 2: Adobe PostScript (PS) is basic file format for all ISO/IEC-test charts and figures. The PS format is e. g. compatible to Adobe Illustrator and Adobe Photoshop. All the tools of these programs can be used to convert to the other file formats, e. g. BMP, GIF, TIF and to change the content of figures. Changes of the PS code will change the output of the PS files and the other file formats.
Remark 3: Based on the ISO/IEC-test charts a combined Input and Output Linearization (IL and OL) can be used to optimize the output of the original scene. There are at least four possibilities (F, S, D, P) to include some standard PS code and the 16 visual or colorimetric grey scale data (or the 8 times 16 colour data for higher accuracy) in the File (F), the Startup (S) directory of the software Adobe Acrobat Distiller, the PostScript Device (D) or the Printer driver (P). The user expects a linear relationship between digital data and visual output. But often there is no Output Linearization by the Printer driver (OLP) or the software-device system. The ISO/IEC-test charts are a new basis for the Input and Output Linearization. The test charts help both users and manufacturers to specify the reproduction properties between input (e. g. original scene or file) and output.
1.11 Visual estimation
of the relative lightness l* of the video output
1.12 Measurement of the 16 grey steps of the video output by a lux meter
1.13 Output Linearization of the File (F) and Startup (S) method (OLF, OLS) for the ISO/IEC-test chart no. 3 on the BAM video projector (BVP)
1.14 Comparison of the outputs with the reference
1.21 Visual comparison
of the lightness L* of the printer output and the ISO/IEC-
or DIN-test chart no. 3
1.22 Measurement of the lightness L* of the printer output by a colorimeter
1.23 Output Linearization of the File (F) and Startup (S) method (OLF, OLS) for the ISO/IEC-test chart no. 3 on the achromatic laser printer (ALP)
1.14 Comparison of the outputs with the reference
Remark: In the poster sessions participants can use computers, copiers, printers (photographic and halftone mode) and measurement equipment of different companies. For the test with analog and digital ISO/IEC- and DIN-test charts the digital Workshop example files are available on the Internet or on floppy disks.
The Figures B4 and D4 of the ISO/IEC-test charts no. 2 and 4 include 8 different 16 step colour series between white and the seven colours CMYOLVN (96 whitish colours on the surface of the colour space and 2 times 16 grey colours). The output of the 16 step series should be equidistant in relative CIELAB colour space for the 8 series. The Output Linearization (OL) uses the files in
2.11 Visual estimation
of relative distance d* of the 16 grey colours in the
video output (compare 1.1)
2.12 Output Linearization (OL) by File (F) and Startup (S) (OLF, OLS)
for 128 standard colours on the BAM video projection (BVP) using 16 greys.
2.13 Comparison of the outputs with the reference
2.21 Visual comparison
of the colour difference d* of 16 grey colours in the
2.22 Measurement of the CIELAB data of the 8 times 16 colours in the printer output by a colorimeter
2.23 Output Linearization (OL) by File (F) and Startup (S) (OLF, OLS) for the 8 times 16 colours of the printer output
2.24 Comparison of the outputs with the reference
All Figures B4 to B7 and D4 to D7 of the ISO/IEC-test charts no. 2 and 4 will be reproduced on one page. The measurement data of the second working section and the Output Linearization (OL) will optimize the video and printer output. The Output Linearization (OL) uses the files in
3.11 Output Linearization
(OL) by File (F) and Startup (S) (OLF, OLS) of all Fig. B4 to
B7 and D4 to D7 of the ISO/IEC-test charts no. 2 and 4 on the
3.12 Comparison of the outputs with the reference
Remark 1: ISO/IEC 15775 defines the properties of an ISO/IEC-test chart image with 32 ISO/IEC-reference colours , which include the 16-step ISO/IEC grey scale and the 16 ISO/IEC-CIE-test colours. A photo of real reflective 32 ISO/IEC-test colours on photographic slide or negative material must be taken together with the scene to produce such an image. The standard photo-CD-process will give 5 resolutions of bit images between 192 x 128, 384 x 256, ... 3072 x 2048 pixels. Participants can use own notebooks and the ISO/IEC-test chart image file B1. This is available on standard 1.4 MB disks in the workshop or during the poster sessions in lowest resolution 192 x 128. There are working PS-files with only 2 x 16 colours in two lines, different e. g. for slide and negative film material between under exposure (of 2 stops) and over exposure (of 4 stops).
Remark 2: The ISO/IEC-text chart image B1 may be taken as a first picture on slide or negative material. Then the Input Linearization (IL) allows to a high degree to get the same output independent of exposure, taking illuminant, film material, developing process, scanning process, software, hardware etc.
Remark 3: Most picture images are based on photographic material and most other Input Linearization (IL) methods fail to handle this standard application. The other methods are dependent on stable input processes but the method used here is to a high degree independent of variations of the input process.
There are two steps, the Input and Output Linearization (IM and OM). The first step is to change the scanning data to equidistant data between 0 and 1 in steps of 1/15 similar as in the original. This leads to standard data in the image file. Then the Output Linearization (OL) of the first working section is used.
Combined Input and Output Linearization (IL and OL) for all colours in the ISO/IEC-test chart image B1 using the 16 grey steps and 7 steps of exposure for slide and negative film material. The method uses the files in
4.12 Use of the
Software Adobe Photoshop to compare the digital scan file data
with the reference file data
4.11 Input Linearization (IL) to change of the scan data to the equidistant data for the grey scale
1. Halftone and
photographic technology, reflectance and transparent mode
3. Accuracy and measurement problems (fluorescent paper)
4. Developing of images B1 for the ISO/IEC-test charts no. 2 and 4 with ISO/IEC- and CIE-reference colours
5. Trend: Taking pictures on slide or negative film with reference colours (ISO/IEC-test chart as reference), using the Photo-CD-process, and the photographic output and the Input and Output Linearization methods on the Internet
6. Linearization methods as a tool for device and ISO/IEC-test chart production
7. ISO/IEC-test chart files for production on BAM-, DIN- and ISO/IEC-web server
8. Database of produced ISO/IEC-test charts in different technologies