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Ultra Violet (UV) and Optical Brightening Agents (OBA) with M0,1,2,3 Measuring Modes

M0, M1, M2, M3 measuring mode settings

These ‘M’ modes have been defined in order to standardise the illumination conditions where Optical Brightening Agents (OBA) are used in substrates, in accordance with the International Standard Organisation 13655 standards.

Here are the 4 different measuring mode settings within the “M” series.

M0 simulates illumination for A (gas filled tungsten).

“Color measuring mode A” spectral luminance factor without polarisation filter under a light source A (gas lamps or LEDs, 2856 ± 100 K, from 420 to at least 700 nm)

Typically used in commercial proofing environments where little or no OBA (Optical Brightener Additives) are accounted for and where the standards values are measured in M0.

If used in Wide Format Print with PrintFactory and where a media contains OBA’s after printing/curing process, then it recommended that “Brightener Compensation” be checked “on” in whichever VISU variants are used (see below).

M1 simulates illumination for D50 (theoretical daylight).

“Color measuring mode D50” spectral luminance factor without polarisation filter under a light source with correct UV component < 400 nm (theoretically F8 fluorescent lamp, in practice only LEDs incl. UV LEDs, 5003 ± 100 K, under 380 to at least 700 nm)

Calculated UV response to emulate UV excitation of OBA‘s (for paper only). For use with ISO 3664:2009 viewing conditions and used in commercial proofing with standards such as Fogra 51L & 52L.

M2 simulates illumination with UV Cut

“Color measuring mode UV Cut” spectral luminance factor without polarization filter under a light source component (gas lamps with UV cut-off filter < 400 nm or LEDs without UV LED, from 420 to at least 700 nm)

M2 (UV Cut), is for measuring:-

High-quality ICC profiles, it allows the measurement effects of optical brighteners (OBA’s), through the comparison with a mode with UV components (M0/A or M1/D50 – depending on the selected illuminant in M2).

This mode is recommended for general use in Wide Format Printing and removes the spurious white point measurements of media containing OBA’s after the printing/curing process.

M3 simulates illumination with UV Cut – helps to reduce differences in measurement due to Specular Reflections.

“Measurement with polarization filter” spectral luminance factor (with spectral scanning spectrophotometer head) with polarization filter pair (in radiated and reflected light, crossing each other) or spectral absorption degree (with RGB filters) under a light source that simulates any standard illuminant (gas lamp or LEDs, from 420 to at least 700 nm).

M3 is for measuring:

  1. Color density (absorption under polarization filter) for Wet Ink press control
  2. Wide gamut inks
  3. Effect pigment inks & Varnish
  4. Printing ink recipes (remission under polarization filter)
  5. Measuring of gloss differential when proofing with matte media or visa versa

Example of Polarisation Filter result

Camera without Polarisation Filter                    Camera with Polarising Filter

Use of M3 filter in a Colour Managed Workflow

Matching a colour patch 

Glossy-Leather sample on top of Printout from Inkjet proofer on paper.

  1. Find colour patch on printout that matches the sample (top left blue arrow)
  2. Compare M3 of sample (second left blue arrow) to M2 of printout (top left blue arrow)
  3. Compare M2 of sample (second left blue arrow) to M2 of printout (top left blue arrow)

If M3 measurements can be correctly used for colour management, the M3 measurement of the sample should match the M2 measurement of the matching colour patch on the printout.

Conclusion on use of M3

  • The M3 measurement condition doesn’t correspond to a real viewing condition
  • Two objects with the same visual appearance can have different M3 and M2 measurements
  • M3 measurements should be used with caution when used for color management 
  • The difference between a M2 & M3 measurement is dependent on the individual properties of the media 
  • The difference between a M2 & M3 measurement is dependent on the individual properties of the media
  • The differences can be very small to extremely large depending on the media properties.
  • M3 measures are typically darker than M2
  • In most cases, M2 will likely produce better results, but in some cases M3 will work better. For some problematic media, neither M2 nor M3 are going to provide perfect results.

Detecting for the presents of Optical Brighteners (OBA)

Using a photo spectrometer. Measure with and without a UV-Cut filter and see the difference in the b value.

If you do not have UV Cut filter for your photo spectrometer measure the b value – if paper looks fairly white but the b value says -5 to 10 ish indicating a blue tinge then you can be quite certain there are OBA’s in it. The more the negative value the more the OBA.

 

Updated on September 16, 2019

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