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The changeover of the old ISO 3664:2000 standard to the 2009 version brought some questions and ambiguities regarding the increased UV content in the D50 proofing light. Questions like: Can old standard fluorescent lamps and proofing stations still be used? How can I recognize if my lens is UV-transmissive? Can I install new standard fluorescent lamps in old units? - were just a few of the many questions about the production changeover to the current standard (» FAQ). With light audits and light measurement technology, the actual status could be determined in case of doubt and ISO 3664 conformity could be reliably verified.

Even if these questions have been clarified for most people in the meantime, a one-time installation of a standard lighting workplace with regular light audit is rarely the case. It is far too risky to produce and color match under lighting conditions that are not clearly validated.

No matter if you buy color proofing lights, stations, tables, booths, LED or fluorescent lamps. With JUST products you can be sure that where JUST is on it there is standard light in it, and it is standard-compliant according to ISO 3664:2009 or ISO 3668.

JUST moduLight Farbprüfleuchte



Even with standard-compliant color viewing solutions, it is advisable to check the light quality regularly, especially for large productions with a lot of color proofing stations. Ambient or interfering light can very quickly cause unpleasant effects and fluctuate greatly from place to place, even within the press room.

Standard lighting workstations are often equipped differently over time. This may be due to new or additional purchases, the use of old and new equipment, or the use of products from different manufacturers. Light conduction and control, the  illuminants and the type of lens are essential parameters in the proofing light and unfortunately vary greatly depending on the manufacturer or type of luminaire.

In addition to prismatic lenses, reflectors, light sources and the luminaire design itself also play a decisive role in the quality of illumination and light.


Lighting audits help here, but depending on the scope and size of production, they are usually an expensive affair and unsuitable for regular monitoring. An independent audit and measurement of the proof stations used can be a more cost-effective alternative.

With our subsidiary GL Optic, we develop precise and intuitive light measurement instruments such as the spectrometer GL SPECTIS 1.0 Touch proGraphic. The light measuring device has a function for reliable ISO 3664:2009 assessment and provides you with all relevant light values. This allows you to independently measure and check all types of light.

Spektrometer zur Lichtaudit
The GL SPECTIS 1.0 Touch proGraphic precisely measures color rendering indices (all Ra values), color temperature (CCT), metamerism indices (MI vis/uv), illuminance (lux), color coordinates, and more.


Select your color proof light or proof station with standard light D50 that you want to check for ISO 3664 compliance. Turn them on and let the lamps burn for at least 15 minutes to stabilize. Consider carefully whether you want a measurement including ambient light or not. Ideally, you should also perform an ambient light measurement on the tuning panel with the lamp switched off so that only the interfering light is measured.


According to the standard, two measurement methods are distinguished, P1: hard copy proofing and P2: soft proofing, as well as two sizes each for the proofing area, < 1 sqm and > 1 sqm. Select the appropriate option for the station and application area in the light spectrometer. Now perform nine measurements one after the other in a 9-field matrix. To do this, place the spectrometer at nine positions on the proofing area and trigger the measurement. The results are displayed immediately and marked in color (red, green) according to the standard conformity.


Back at workstation, you can import and evaluate the measured values using the GL SPECTROSOFT light analysis software. If you do not have a mobile spectrometer, you can also connect your spectrometer (e.g. the GL SPECTIS 1.0) to your laptop directly at the proofing area and then perform the ISO 3664 measurements using the software. No matter which spectrometer you choose, you will get exact measurements with our GL spectrometers series in any case!


With the GL SPECTROSOFT software, you can automatically generate a ISO 3664 measurement report at the push of a button. This report is modular and individually structured. This means that you determine in the software which values are to be included in the ISO 3664 report and which diagrams or curves are to be output. Ideal for the clear presentation of relevant key figures of the measured lighting situations.

ISO 3664 measurement in video

You have any questions?