Re: M1 measurement mode
Re: M1 measurement mode
- Subject: Re: M1 measurement mode
- From: Claas Bickeböller via colorsync-users <email@hidden>
- Date: Thu, 13 Jun 2019 10:45:31 +0200
Roger,
maybe this article clarifies things?
https://www5.konicaminolta.eu/en/measuring-instruments/learning-centre/colour-measurement/colour/iso13655-demystified.html
<https://www5.konicaminolta.eu/en/measuring-instruments/learning-centre/colour-measurement/colour/iso13655-demystified.html>
Short: M0 = undefined UV. If a fresh tungsten lamp is used in an M0 instrument
the OBA is excited nearly like with illuminant CIE A which means that the
fluorescence is weaker than with D50 (M1).
This leads to more yellowish readings (also a more yellowish appearance in a
viewing environment that has the same UV energy as CIE A).
But as M0 is undefined a different M0 instrument can theoretically excite the
OBA even more than D50 (e.g. the old Avantes Spectrocam).
Best regards
Claas
> Am 12.06.2019 um 23:33 schrieb Roger Breton via colorsync-users
> <email@hidden>:
>
> Dear ColorSync List,
>
>
>
> Today, I was working on an Epson 7890 printer at a client.
>
> According to my automated spectrophotometer, the measurement I got off my
> client proofing substrate was :
>
>
>
>> 95 0 -2.3 in M0
>
>
>
> I know I have a choice of M0/M1/M2 CIE Lab coordinates off this instrument.
> But in the heat of things (I had all kinds of troubles.?), I did not pay
> attention to the possible differences between each and stuck with M0.
>
>
>
> My handheld instrument (tungsten illumination M0 only) gave me :
>
>
>> 95 0 -3.5.
>
>
>
> A higher negative b* value. I know, it is not a huge difference.
>
>
>
> In general, does M1 "reduces" fluorescence, much like "M2" UV filtering or
> does it "increase" its value?
>
>
>
> In "theory", I would think that M1 makes an optically brightened paper more
> "b* negative", so that, an M0 instrument, which does not stimulate much UV
> fluorescence in the 360nm range, would give a b* = -3.5.
>
>
>
> But what is the "real" story behind M1? Is it to cause the substrate to
> fluoresce "more", by throwing more UV energy at it? Therefore, causing the
> b* to be "higher" than -3.5? Like -5.00 or -6.00?
>
>
>
> Or is it supposed to yield a b* less than -3.5, as in the case of this
> proofing paper?
>
>
>
> I confess I have to do additional readings on the subject.
>
> (I can be such a newbie at times.)
>
>
>
> But here is what I do *know* will happen, from experience : if the substrate
> appears more bluish (higher b* negative value), because of M1 higher UV
> illumination, therefore, the proof will appear more "yellowish", in Absolute
> Colorimetry, that has always been my experience, for a Source print process
> that has a b* closer to zero.
>
>
>
> But if the substrate appears "less bluish", because of M1 illumination, then
> the proof will appear less yellowish, in AbsCol.
>
>
>
> Does that make any sense?
>
>
>
> I really need to brush up on my understanding of M1.
>
> Thank you in advance for your patience and help.
>
>
>
> Best / Roger
>
> www.graxx.ca
>
>
>
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